Shell is brittle, plump and equivalve. Inequilateral, beaks in front of the midline. Oval in outline with the ridge of the escutcheon approximately straight, almost horizontal, curving abruptly to the obliquely truncated posterior margin. Lunule small, indistinct; escutcheon poorly defined, lanceolate, with a straight elevated ridge, the dorsal posterior margin of the shell, running through the centre. Shell surface smooth, with very fine concentric lines. Growth stages are clear but not prominent. Hinge line with 10-12 teeth in the anterior group and 12-16 posteriorly. Adductor muscle scars and pallial sinus are indistinct; the sinus is shallow. Margin is smooth.
Up to 6.3 mm in length.
Periostracum is glossy, greyish green in colour.
It has a wide distribution in the northern hemisphere, extending across the Arctic from Greenland to Novaya Zemlya and south to North Carolina and the Mediterranean (Distr. Y. lucida).