The Green River in Mammoth Cave National Park contains the most diverse population of freshwater mussels in North America, and one of the most diverse populations in the world. Among the species found in the river are the Ring Pink, Rough Pigtoe, Pistolgrip, Fatmucket, Spectaclecase, Plain Pocketbook, Washboard, Sheepnose, and Snuffbox. Several of the mussel species are federally endangered. A snail (Antroselates spiralis) is found in cave environments.