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Family Eulimidae

HAWAII

Thyca crystallina

Top center, Palea Point, Oahu, 30 feet

PARASITIC CAP SHELL

Glassy, ribbed, limpet-like shell attached to underside of Spotted sea stars.  Sucks bodily fluids from its host.  Rarely seen.  Attains 0.5 inch.  Hawaii & the Indo-West Pacific.  The lump on the sea star's upper surface (underside in photo) indicates the presence of the Linckia Gall Shelll, Stilifer linckiae.