This area of the Pacific coast of Mexico and Guatemala, probably the site of several pivotal stages in the development of Central American culture, was occupied from pre-Olmec times (about 1500 B.C.) up into the Mayan era. The site had more than 80 large temple mounds and an enormous collection of richly carved gods, animal figures, and scenes of travel and warfare. Altars and elaborately carved scenes of mythological events were everywhere. Many of the figures were oceanic--one was a fish/human creature. I looked at the pyramids, the long narrow ball court, the monuments, and the altars with strange carved figures of men in boats wearing feathered headdresses riding waves filled with monstrous fishes. There were carvings of jaguar gods, serpents, and monsters with men standing in their mouths.

"This is where it all began," Vince said, his eyes glowing. "These people, whoever they were and wherever they came from, worshipped the sun. My research has shown that all the pyramids, the ball courts, and the monuments are aligned either to the mountains or to the summer or winter sunrise solstices. I'm convinced the calendar began here. And so did the Olmecs. That's what I'm mainly interested in. This magnetic turtle of yours is just a sideline for me--a digression."

"Where is the turtle?" I asked, taking in the great number of stones and stelae, anxious to finally see it.

"I'll show it to you, but before I do I want you to see something."

We followed him across the ball court to a faded, broken stela. There on the worn, etched rock was a carving of a man standing in a boat holding a cross, which some archaeologists have interpreted as a cross staff, a navigational instrument. It appeared that he had a beard, and beneath his canoe were a number of bizzare, stylized fish. Etched beneath the boat were spiraled renditions of rolling waves, and two hook-nosed deities looked on from each side. They seemed to be the wind gods blowing the current each way.

"Nowhere else is the seafaring mode so prominent," said Malstrom. "I believe Izapa had early contacts with the sea. And it may have been visited early on by navigators from distant regions." His eyes shown with excitement. "The methods used to predict solar and lunar eclipses are virtually identical for both Han dynasty Chinese astronomers and the Mesoamerican cultures. Likewise, their methods for making bark paper were also identical. They were a seafaring people; they spread their influence to the New World and traded all along this coast, all the way down to Ecuador. We can tell this based on their pottery.

"And they lived at a time when sea turtles were prevalent in all the oceans. When they made their long sea journeys, they doubtless sustained themselves on these animals. Turtles were easy to harpoon, and they could be stacked up in a boat and kept alive for weeks or months."

Then he pointed to a group of stones and stelae near the entrance of the site, which was now a park with well-trimmed grasses. "Your turtle head is over there."

We hiked over, and the tall, reserved professor suddenly grew angry at the sight of a makeshift barbed-wire fence that had been thrown up between the monuments.

"This is an outrage," he cried, as if personally insulted. "Someone has turned this into a hog pen." Almost in response, several pigs got up, grunting, and moved out of our way. I wasn't interested in the hogs. Here, at last, was what I had come to see.

Compared to the other structures, the turtle head was unimpressive. It was a large black boulder about four feet long and three feet wide, sitting there among the rest of the carved stones about 60 yards south of the ceremonial ball court. Sometimes when you see a photograph you think there will be more when you actually go up and touch the object and see for yourself. But that wasn't the case. This turtle with its dark, brooding eyes and chiseled-out features was just as bizarre and enigmatic sitting there in its three-dimensional state as in the black-and-white photos I'd seen in Malmstrom's article in Nature. In fact, it appeared less impressive because it was lost among all the other stones.

"Go ahead," Vince urged, "check it out. That's what you've come all this way for."

I stepped forward clutching my compass, hoping that I would get some sort of blinding revelation that this long trek would be worthwhile after all. I held the compass steady, and when the dial stopped turning and remained fixed at 110 degrees, I slowly, steadily thrust my hand and compass forward. Suddenly the field of force gripped my compass and the needle whirled to the north, coming to rest at 60 degrees. The force was much more powerful than that of any statue we had measured so far. My hand was trembling with excitement and bewilderment, but I held it there, and when I withdrew it the dial spun back to its original position of 110 degrees. Again and again I tried it with the same results. No matter where I moved the compass around that great stony face, the needle continuously pointed to the snout until I pulled it away. Half a meter away the magnetic field faded and the turtle's nose lost its pull.

I was more bewildered than ever. The rock could speak to my compass but not to me. Somehow I hoped a lightbulb in my brain would switch on, but there was just blankness. Had I come all this way and spent other people's money just to watch a needle jump?

Then an image flooded into my mind of a real flesh-and-blood green turtle coming ashore to nest. There in the fiery surf, the great creature bends its head down and nuzzles the sand, as if smelling the ground, perhaps to see if it is in the right place before hauling its great girth up the beach. And it was in the olfactory lobes of the brain where Joseph Kirschvinc of Cal Tech first discovered the ferromagnetic crystals.

Again I took a reading, doubting what I had just seen. Vince laughed. "It's the damndest thing, isn't it? I don't know what to make out of it, all I did was describe it. As I wrote in my article in Nature, the sculptors may very well have associated magnetism with the migrations of sea turtles and rendered it."

Was Malmstrom right? Was this magnetic stone indeed the origin of the Turtle Mother myth? Was the legend or religion really ancient? My search to find the Turtle Mother had started so innocently, so casually, just from something I had heard, but it stuck in my mind, and I couldn't drop it. This quest had just about taken over my life.

Turtle Mother was only a shadow of a myth, told by old men in villages along the Caribbean shores of Honduras, Nicaragua, Costa Rica, and Panama. With each passing year, the old turtlemen who knew the old ways, who had lived in close relationship with the land and the sea, were dying off. And yet, somehow, the thread of the myth had survived, at least in the Caribbean. In Nicaragua and Costa Rica the tale was repeated with such consistency, almost by rote, that I couldn't believe that this myth sprang out of thin air. I felt in my bones that it had some basis in solid fact, that it was related to magnetic orientation, and while Malmstrom's magnetic turtle head didn't prove it, it added a strong piece of circumstantial evidence. The turning of a compass needle in the legend added another. And so did all the millions of submicroscopic ferromagnetic crystals torqueing in the brains of sea turtles as they migrated across thousands of miles of ocean between breeding beaches and feeding grounds.

There was no way the old turtlemen of the Miskito coast could have known about ferromagnetic crystals. Yet they said that this magic rock, in the shape of a turtle, turned like a compass needle. And there was no way the pre-Olmecs, who carved the magnetic turtle head, could have known that either.

Looking at the rigid head, that chunk of magnetic stone, the first tangible piece of evidence that Turtle Mother existed, I pondered the great migrations of olive ridleys and the Chelonia agassizi turtles, a separate species of green turtle, that swarm the Pacific coast of Central America. Unlike the diminished Kemp's ridley in the Gulf of Mexico, which is on the verge of extinction, there are hundreds of thousands of olive ridley sea turtles. They swarm ashore on beaches from Mexico to Panama in such multitudes that they dig up each other's eggs. In spite of Mexican turtle factories up and down the coast that slaughtered them by the tens of thousands for their hides until they were banned in 1986, and in spite of the wholesale exploitation of their eggs that destroyed entire nesting colonies, olive ridleys remain the most abundant sea turtle in the world, with mass nestings in India, Africa, and Asia, as well as in Central America.

If there were such multitudes now, how many must there have been when the people who carved the stone turtle fished along the sea? Yet here was another great mystery, for nowhere in the kitchen middens (the garbage heaps of the pre-Columbian people who lived on both, sides of the isthmus) has anyone ever found the first ridley bone, skull, or piece of shell. Zooarchaeologists have unearthed plenty of remains of green turtles, hawks bills, loggerheads, and even a leatherback bone or two, but not the first sign of any ridley-Kemp's or olive. Were they taboo, or was this abundance something new?

As we were discussing all this, the old caretaker, who lived in an adobe hut at the site and kept the grass cut, wandered over, collected two pesos from each of us, chatted with Vince in Spanish for a few moments, and left.

"They charge according to the importance of an area," the professor explained. "Uxmal, where the big pyramids are, is a ten-peso site. Someday I hope to make Izapa equally important. Over the years I've discovered that more than forty ceremonial centers in Central America are precisely aligned to the summer or winter sunrise solstice. Izapa is the oldest and perhaps the most important of them."

The pigs that rooted around the stelae belonged to the caretaker. This irreverence irritated Vince, especially since the newly placed hog pen ran right between the turtle head stela and the upright altar behind it.

"This is a disgrace! I'm going to write to the Minister of Archaeology in Mexico City when I get back," he said, snapping a picture for evidence.

I had to step over the wire fence into the soggy mire of the hog pen to scan the black snake head that stood in a direct line in front of the turtle. Even though it was only a crudely carved boulder, it caught the essence of serpents, staring ahead with its own fixed rigidity. Just as Malmstrom had reported in his paper, it was not magnetic. Once again an image flooded into my mind: a big black indigo snake that we saw recently in the Everglades lying at the edge of the water, with brilliant glossy coal black skin and scales of hexagonal and diamond shapes.

Again I saw its long black tongue whipping in and out, tasting the air, testing for an unfamiliar smell in the green world. Its eyes looked like black jade, and it moved over the ground in a smooth sinuous motion, sliding majestically into the water where the sunlight poured down through the leafy vegetation. For a moment its coal black scales gleamed with beauty until this rare and endangered creature vanished, spiritlike, into the mangroves.

The snake here was a strange coincidence, for over and over again in Chinese motifs a tortoise and a serpent appear intertwined. And even in American folklore it is said that if a turtle crawls through the marsh, it will be followed by a snake. Rattlesnakes routinely inhabit burrows made by gopher tortoises along the southeast coast and the two live together in a comfortable symbiosis of some sort. How much of this was coincidence, piling up fragments that might have absolutely no connection with each other, and how much was real, I had no idea. I took another reading on the black snake head, and still nothing. Then I started methodically pointing my compass at all the other rocks and altars.

"Go ahead," said the professor in a bemused tone. "Do them all. You won't find anything else magnetic. When I first found this thing I must have checked half the cobblestones in the ball court, but nothing else here is magnetic. But the turtle's about twice as strong as the monuments we found in Guatemala yesterday."

I looked wearily at all the other basaltic boulders strewn around the site, some carved, others not. I tested them; all were negative. A nearby river was filled with rocks, many the size of the turtle head and just as black. I waded out and tested them also until I finally came back and sat down, weary of pointing my compass at every mineral and getting nothing. I sat on the turtle rock, running my hand over its smooth water-polished surface. "You really don't think there's a chance that all this could be coincidence?

"You see how much luck you've had finding a magnetic stone. Sure it could be random, but I doubt it, now more than ever, especially after what we just saw in La Democracia and El Balli. As I said before, I think they deliberately fashioned this rock so the magnetic lines of force came to focus in the snout." On this point, Vince was unshakeable.

Anne ran her hand over the smooth black rock. "The stones are going to keep their secrets," she mused. She looked at all the other stones, stelae, and monuments. "How did you find this thing?"

Vince said, "It was the sheerest of accidents. One of my students was doing her research paper on the role of the serpent in Mesoamerican art and we were checking to see if the snake sculpture had any particular orientation. Even though that turned out to be negative, when we checked the turtle sculpture behind it, the compass needle went crazy.

"You can imagine it's been pretty controversial. A lot of people don't believe it. There's even some dispute as to whether it's really even a turtle. The archaeologists who first excavated it in 1963 called it a frog. What do you think?"

I looked back at those rigid down-turned jaws. "It looks like a turtle to me. Since the guy who carved it isn't around, and isn't in a position to say, and I've come this damn far, it's a turtle."

Suddenly I wondered who the priest was who first hauled this rock down from the mountains or dragged it up from a dry riverbed and chiseled out those features. Whoever he was, he went to a great deal of effort to chisel and polish it so the magnetic lines of force were centered in the nose. Not in the eye or the side of the head or the lower jaw, but specifically in the nose.

I looked at my wife questioningly, hoping she'd have some answers or at least some observations, since she was our resident scientific skeptic, always prepared to come up with a rational approach. "You could read it either way," she said matter-of-factly. "It looks more like a turtle than a frog to me."

We wandered around Izapa for hours, until the sun was starting to set. "Well," Vince said at last, "Paul and I have to be pushing on. You're welcome to accompany us up the coast if you like."

Anne and Nikkie looked at me, awaiting my decision. A great feeling of hopelessness swept over me. I had no idea what to do next. Had we been on a collecting trip, to bring back some weird shark or speckled nudibranch, I could have coped. I could ask questions, explore new habitats, try a different kind of trap or net. But now I was lost. Certainly there was no real story here. All that happened was the rock made a needle jump. I could have predicted that before I left. The logical part of me said go home and cut off these outlandish expenses. But I couldn't do that.

"I don't know what to say," I admitted. "I haven't found Turtle Mother, or a magic rock that revolves. I can try to whip this into some kind of story, but nothing happened. The truth is, we haven't learned any more about this turtle head than what you wrote in your article. So I don't know where to go from here."

"There is another possibility," Malmstrom said thoughtfully. "There's an old civilization up in the mountains about a hundred miles further up the coast called Tonala. I understand that they have some primitive-looking animal sculptures up there and there may be turtles there too.

"I've always wanted to go there," he said, his voice turning wistful. "Several years ago I tried to climb that mountain and take readings on the pyramids. But I got hopelessly lost. We're short on time, and I've got to be in Oaxaca the day after tomorrow for an appointment. But if we get lucky and find a guide, and we could get up there and back in a day's time. I'd like to try it again and you might find a turtle rock."

Once again we piled into our vehicles and headed down the highway. Never had we spent so much time on the road, searching for God knows what. "Well, you found a compass needle that turned," Nikkie said optimistically, as we settled down for the long drive ahead. "When you put it next to a magnetic rock, the needle turns just like the Turtle Mother does in the legend. That's something, isn't it?"