Littleneck clams are small, hard-shelled clams with a shell diameter of less than 2 inches. They are harvested on both the East and West coasts of the United States. These clams have a slightly chewy texture and a flavor that runs from sweet to salty. There are many ways to cook littleneck clams. Most often, they are served raw on the half-shell or in pasta dishes. They can also be steamed and served alone.