Distribution: South Carolina to Texas; West Indies. Size: Diameter 3 mm; altitude 1 mm. Description: Color translucent white in live or fresh material to opaque in dead specimens; shape discoid, not planispiral, shell thin and com-pressed; sculpture smooth with the exception of irregular, wavy axial and sometimes spiral growth lines; spire flat or sunken and partially covered with a thin, translucent callus; teleoconch with 2 adpressed whorls; umbilicus wide and shallow; aperture oblique to ovate. Habitat: Found beneath the scales of the annelid worm Acoetes lupina. Depth range 0 to 48 m (157 ft).
Remarks: The distinct growth lines give C parasitica a nautiloid appearance, and the color of the living animal is red. The parasitic name is misleading because the animal lives commensally with the tube worm, feeding on algae and/or detritus found within the elytra of the polychaete annelid. See Moore (1964); Ode (1969c); Andrews (1977). Synonym: Adeorbis nautiliformis Holmes, 1859.