Shell medium to large, 40mm to 60mm. The attached left valve large, deep and the right valve flat or slightly convex and covers the left one like a lid. Shape varies with the stage of growth and the type of substratum. In the spat, valves translucent and pearly white, but turns opaque dull white as they grow. Anterior and posterior margins of the valves at the umbonal region at an angle of more than 20″ to the baseline parallel to the hinge. Hinge situated right at the valve margin and does not form a beak. Right valve usually has a brownish band extending from the umbo on the dorsal side to the ventral margin. Valve margins usually sharp and indented with angular folds decorated with laminae.