Lives attached to the anal spines of some species of sea urchin (Spatargus purpureus and Echinocardium florescens) usually in realtively coarse sediment.
- Presence of teeth on the hinge
- Sculpture of obvious radiating ribs
Fragile shell up to 3mm in length. White to translucent both inside and outside. The surface of the shell is sculptured with radiating ribs and faint concentric lines.