Shell small to medium sized, equivalve, almost equilateral with umbones at the anterior part. Outline variable usually subovate, distinctly longer than high but many are shortened posteriorly, becoming rhomboidal with a rather straight high posterior margin. Sculpture of concentric lines and ridges which may be a little irregular at the posterior part. Hinge with 3 cardinals in each valve and prominent anterior laterals. Very small pallial sinus. Internal margin smooth.
extremely variable; white, cream to yellow shell with patterns of zig-zag / radial rays, or two different tones of brown. Umbonal area usually pale orange.
common size :
to 35 mm in length; in the Arabian Sea to 50 mm.
The absence of a flattened umbo, radial sculpture and the ovate rather than trigonal outline are diagnostic features for the species. It is the unique species of the genus in the Red Sea and has no congeneric in the Mediterranean.
BIOLOGY / ECOLOGY
sands in shallow water; also in sandy mud at mid-tide level (Bosch et al., 1995).