Ensis directus has a thin, elongated shell that is slightly curved. It ranges from yellowish to dark brown in color. The length of E. directus is about six times its width. It can grow to be about 10 in. It has a coating around its shell to protect it from eroding in the mud or sand. Ensis directus is a bivalve, which means that its shell has two parts. The body of Ensis directus is surrounded by the mantle and the mantle is seperated into two parts. Each part of the mantle secretes a shell. The two shells are connected by an elastic ligament that allows for it to open and close. Both parts are usually identical and are made up of calcium carbonate and protein. It has a huge foot that allows it to move through water or to burrow in the sand. When the foot is extended all the way, it is almost as long as the clam's body.

(Alexander 1979; Lippson 1984)