Glycymeris nummaria

Glycymeris nummaria is a species of saltwater clam, a marine bivalve mollusc in the family Glycymerididae, the bittersweet clams.

Synonyms

 * Arca insubrica Brocchi, 1814
 * Arca nummaria Linnaeus, 1758
 * Glycymeris insubrica (Brocchi, 1814)
 * Glycymeris violacescens (Lamarck, 1819)
 * Pectunculus cor Lamarck, 1805
 * Pectunculus nudicardo Lamarck, 1819
 * Pectunculus obliquatus Rayneval & Ponzi, 1854
 * Pectunculus pilosellus Risso, 1826
 * Pectunculus purpurascens M' Andrew, 1854
 * Pectunculus reticulatus Risso, 1826
 * Pectunculus transversus Lamarck, 1819
 * Pectunculus zonalis Lamarck, 1819

Description
The shell of an adult Glycymeris nummaria can be as large as 60 mm. It is quite thick, almost circular in shape, with a sculpture of radiating striae and fine concentric lines. The surface is dull and may be dark or pale brown, but also whitish-yellowish. Inside of the shell is glossy, white or pale yellow, often with irregular brown markings.

Distribution and habitat
This species is widespread from Norway to the Mediterranean Sea. It lives in sandy-muddy gravels offshore to depths of about 100 m.