The Atlantic surf clam (Spisula solidissima), also called the bar clam, hen clam, skimmer, or simply sea clam, is a very large, edible, saltwater clam or marine bivalve mollusk in the family Mactridae. It is commonly found in the western Atlantic Ocean. Reaching up to 20 centimetres (7.9 in) or more in length, it is much larger than the related surf clam, which resides in the eastern Atlantic waters off of Great Britain.