(Clarck W., 1852)
Description (shell):
Shell thin and fragile, inequilateral, umbones posterior to midline; obliquely oval. Sculpture of very fine concentric lines and irregular, radiating striations; growth stages clear. Each valve with one cardinal tooth and single anterior and posterior lateral teeth; distinct in right valve, less so in left. Adductor scars and pallial line indistinct.
Size:
Up to 2 mm in length.
Colour:
Colour yellowish white, periostracum indistinct, visible as darker bands about the growth stages.
Animal:
The mantle, which is fringed with long tentacles, protrudes nearly all round. The foot can be flattened in such a manner that it resembles the foot of a snail and it is used in similar fashion.
Habitat:
Distributed from the lower shore into the sublittoral, in association with various species of sipunculid.
Distribution:
Reported from south and west coasts of the British Isles (Distr. E. clarkiae); present in Mediterranean.