Habitat: it seems it prefers sandy and muddy bottoms of the infralittoral zone. Distribution: even if never common, it is present in a large part of the Mediterranean.
Notes: shell not much changeable in form and in colour pattern. Roundish in outline, central umbo not much protuberant. Umbonal area smooth. Very characteristic valves sculpture: they are crossed obliquely by several elliptical grooves starting from the posterior side, near umbo, up to the anterior margin. The hinge of the right valve has one principal tooth only, while the left valve has two divergent teeth. Valves internal margin crenulated. Fresh specimens are dark brown in colour either with streaks or radial striae lighter. Apart from umbo which is more protuberant, juvenile specimens are not so much different from adults as far as the outline is concerned. The measures of the adult specimens are around 6-7 mm in diametre.