The Higgins-eye mussel (Lampsilis higginsi ) is an inhabitant of large rivers in the Mid-west. Once more common the Higgins-eye is now restricted primaily to the main channel of the Mississippi River and is a federally endangered species. Prefered substrates appear to be gravel, sand, or mud. The shells are thick and heavy, and yellowish-brown in color with green or dark rays. They are rounded-oval in shape, have relatively smooth shell, and can grow to ~ 4 inches in length. As with other lampsiline mussels females have a distinctly expanded posterior and display a modified mantle margin that resembles a small fish.