Shell large, light, inequivalve, inequilateral. Outline discoid, with small ears unequal. Lower valve flatter. Upper valve slightly convex with sculpture of numerous fine ribs and finer riblets between them. Surface rough.
externally lv cream, rv white with pink spots at the umbonal area. Internally also glossy white with pink spots.
common size :
45-75 mm in length; the Mediterranean record 46 mm.
Similar to C. islandica (Müller, 1776) which lives in the North Sea. Can be confused with Zygochlamys patagonica (King and Broderip, 1832) which is smooth and very convex. The latter has almost square riblets and fine concentric lines (Rombouts, 1991).
BIOLOGY / ECOLOGY
in rocky substrata and detritic bottoms. The northwestern Sicily record at 25 m (Repetto, pers. comm.).