Native littleneck clams have an oval to round shape and they grow up to 3½ inches long. The shell exterior exhibits concentric rings with radiating lines that form a lattice pattern. They may be cream or grey coloured and may display a variety of different patterns. The anterior (lower) side of the hinge of the native littleneck clam typically has a pronounced ridge, whereas the same location on the Manila clam is indented.

Native littleneck clams are buried 4 to 6 inches deep in cobble, gravel, sand or mud substrate and they normally occur in the mid-intertidal zone.