The shell is rather small for the genus, subquadrate, squared to rectangular with the ventral margin projecting posteriorly; the outside, yellowish to brownish, bears irregular scales arranged concentrically; the inside has a nacreous core, markedly recessed, white to blue, surrounded by well developed margins that are of the same colour than the external surface; each valve bears a double muscle scar (comma-shaped coalescence) on the anterior side.