The freshwater pearl mussel, scientific name Margaritifera margaritifera, is an endangered species of freshwater mussel, an aquatic bivalve mollusc in the family Margaritiferidae. Although the name "freshwater pearl mussel" is often used for this species, other freshwater mussel species can also create pearls and some can also be used as a source of mother of pearl. In fact, most cultured pearls today come from Hyriopsis species in Asia, or Amblema species in North America, both members of the related family Unionidae; pearls are also found within species in the genus Unio.