This clam is distributed on the west coast of North America from Alaska to California. Eastern softshells were thought to have been introduced to the west coast from the east coast of the United States in shipments of oyster seed. Recent studies, however, indicate that they may be native to this coast. They are medium-sized clams, with shells which are easily broken. Softshell clams are often mistaken for small horse clams. The shell is rounded at the foot end and rather pointed at the siphon end. The external surface of the shell is marked with uneven concentric rings. They have brittle, thin elongated shells, colored chalky-white to gray with brown or yellow periostracum at the edges. Their siphons are dark. This clam, as well as other clams in this genus, has a large spoon-shaped structure in the inside of the left valve near the hinge. The shells gape, but the clam is able to completely retract its body within the shells. Soft shells are normally found in sand and mud, and are most abundant in the upper half-tide level near river mouths or heads of bays where low salinity water occurs. Soft shells normally bury to a depth of 8-14 inches, and are taken with shovels or standard garden forks by sport diggers. These clams are not as popular with sport diggers in Puget Sound as are butter or littlenecks. A small commercial fishery has recently developed on these clams on private intertidal ground in Skagit Bay and Port Susan, where extensive beds exist. This species is highly prized for food on the Atlantic Coast and contributes to an important commercial fishery there.