(Montagu, 1808)
Description (shell):
Shell thin and brittle, elongate-oval to fusiform, approximately twice as long as deep. Sculpture of very fine concentric lines, visible with hand lens. Growth stages indistinct. Chondrophore slender, posteriorly directed. Right valve with two small cardinal teeth anterior to chondrophore, and single anterior and posterior lateral teeth; left valve with one small cardinal tooth, and poorly developed single anterior and posterior laterals. Rendering adductor scars and pallial line indistinct. Pallial sinus with lower edge partly fused with pallial line (A. prismatica-drawing).
Size:
Up to 13 mm long.
Colour:
Outer and inner surfaces white, glossy.
Animal:
Very active. Pearly white. The foot is large and pointed; the two siphons are slender; the mantle edges are finely fringed.
Habitat:
In mixed sandy bottoms, from the lower shore to about 60 m.
Distribution:
Widespread in the North Sea (Distr. A. prismatica), distributed from Norway to the Mediterranean and north-west Africa.