P-50 HERMIT CRAB SPONGE, Pseudospongosorities suberitoides

It is a hardy, commensal orange and green sponge that engulfs hermit crabs or snail shells, building up layers of sponge tissue called “false shells.” When the sponge colony is small, the crab or snail moves freely around the tide flats, but when Pseudospongosorites grows too large the host becomes a trapped prisoner. Paguristes hummi, the filter-feeding hermit, or Cantharus cancellarius, the ribbed snail are the original hosts. Size: 3-6 cm.