<Tr> <Td_colspan="2"> Margaritifera margaritifera (Linnaeus, 1758) </Td> </Tr> <P> The freshwater pearl mussel (Margaritifera margaritifera) is an endangered species of freshwater mussel, an aquatic bivalve mollusc in the family Margaritiferidae . </P> <P> 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 . </P> <P> The interior of the shell of Margaritifera margaritifera has thick nacre (the inner mother of pearl layer of the shell). This species is capable of making fine - quality pearls, and was historically exploited in the search for pearls from wild sources . In recent times, the Russian malacologist Valeriy Zyuganov received worldwide reputation after he discovered that the pearl mussel exhibited negligible senescence and he determined that it had a maximum lifespan of 210--250 years . The data of V.V. Zyuganov have been confirmed by the Finnish malacologists and gained general acceptance . </P>

Can you find a pearl in a mussel