How does a bivalve create a pearl?

1 Answer
Jun 10, 2014

Almost any shelled mollusk can, by natural processes, produce some kind of "pearl" when an irritating microscopic object becomes trapped within the mollusk's mantle folds, but the great majority of these "pearls" are not valued as gemstones.

Nacreous pearls, the best-known and most commercially significant pearls, are primarily produced by two groups of molluscan bivalves or clams.

A nacreous pearl is made from layers of nacre, by the same living process as is used in the secretion of the mother of pearl which lines the shell.