Mysella bidentata

(Montagu, 1803)

Description (shell):
Shell thin and fragile, oval, the umbones are posterior to midline. Sculpture of fine, closely spaced, concentric lines; growth stages are clear. Each valve with a single anterior and single posterior lateral tooth. Adductor scars are about equal, distinct; pallial line is broad.

Up to 3 mm long.

White or translucent, periostracum light brown or olive. Inside of shell is white.

The mantle has its margin fringed and forms a very brief tube behind. The large broad foot is somewhat triangular in outline.

From ELWS to about 100 m, in muddy sand or fine gravel, in crevices of dead oyster valves, in the burrows of the sipunculid Golfingia , or associated with the ophiuroid Acrocnida brachiata .

Common in the whole North Sea (Distr. M. bidentata), it ranges from Norway to West Africa and the Mediterranean.