Ruditapes decussatus, or Venerupis decussatus. Carpet shell clams or palourdes are mostly caught off the coast of Brittany, and since 1970 have been raised in aquaculture farms there, in Normandy and in the Vendée.
They are often served raw on a seafood platter with lemon, or cooked with butter and garlic, with spaghetti or in chowder (chaudrée aux palourdes or soupe aux palourdes).
Image by Judgefloro