Shell is solid, equivalve; inequilateral, beaks in front of the midline. Broadly oval in outline. Ligament reaching about one-third the length of the escutcheon. Sculpture of up to 25-30 prominent broad concentric ridges and numerous concentric lines. Lunule and escutcheon are prominent, each with fine radiating lines. Growth stages not clear. Right valve with two cardinal teeth, a broad anterior and thin posterior; anterior is variable in shape and may be so deeply bifid as to look like two teeth. Left valve with three cardinals of which the posterior is very inconspicuous and may be broken off. Margin is smooth.
Up to 3.2 cm in length.
White. Periostracum with a fine mesh-like structure, dark brown or red-brown in colour.
Body almost round, flattened from the sides. The lips are large; the mantle is thick, not fringed with tentacles, but part of it forms a short excretory siphon behind. The foot is conical and small, though powerful.
Generally in sandy mud and gravel offshore below 5.5 m.
Only from northern waters (Distr. A. elliptica). Distributed from Greenland across to the Kara Sea and the White Sea south to the W. Baltic, the British Isles, the Faroes, Labrador and Massachusetts.