Hard Clam on White Background - stock photo

The hard clam (Mercenaria mercenaria), also known as a quahog, round clam, or hard-shell clam, is an edible marine bivalve mollusk. It is also known as the Northern quahog, round clam, or chowder clam. n fish markets there are specialist names for different sizes of this species of clam. The smallest are countnecks, next size up are littlenecks, then topnecks. Above that are the cherrystones, and the largest are called quahogs or chowder clams.