Lampsilis siliquoidea is recognized by its brown shell with dark rays, and is usually about 70 to 100 mm in size. The shape of the shell is oblong to elliptical, compressed or inflated, with uniform thickness. Fatmucket clams are filter feeders. They feed on algae, phytoplankton, protozoans and organic particles. In the parasitic glochidial stage they feed on blood from hosts species, which include bass, perch, walleye, and sturgeon.
It is widespread in North America, found in the drainages of both the Mississippi River from New York to Minnesota, the Great Lakes, and Hudson Bay. It lives in lakes, rivers, streams and quiet waters, usually on sandy-mud bottoms.