Pisidium amnicum is a species of very small freshwater clam, sometimes known as the greater European peaclam or the River pea shell. It is an aquatic bivalve in the family Sphaeriidae.
Although only 9 mm (range 7âÂÂ11 mm) in length, this species is considerably larger than most Pisidium species, and has a fairly thick, concentrically ridged shell. Its shell is solid, glossy, triangular-oval in shape, and has broad but not prominent umbos often coated with a dull ferruginous deposit. Its colour is grey-white to brown, often with a greenish cast.
Its native distribution is Palearctic. The species has been introduced to northeastern North America.
In Europe, it requires clean water and high levels of calcium.