The shells of river clams are medium in size and have a round-bottomed triangle shape. The height of the shell is similar to that of the shell. The two shells are expanded, and the top of the shell is high and slightly forward. The surface of the shell is shiny, and the color varies with the environment, often brown, yellow-green or dark brown. The shell surface has rough ring ribs. The ligaments are short and protrude from the shell. The twisted part is well developed, the adductor muscle marks are obvious, and the coat marks are deep and prominent. River clams live in freshwater lakes, ditches, ponds and rivers where brackish water meets, and are widely distributed in inland waters of our country. It is distributed in Russia, Japan, North Korea, and Southeast Asian countries.