Natural freshwater pearls occur in mussels for the same reason that saltwater pearls occur in oysters. Foreign material, usually a sharp object or parasite, enters a mussel and cannot be expelled.

The largest Scottish ... in Scottish rivers contains a pearl, and generally they are smaller than their saltwater ...

The dearth of akoyas has helped open the door for other kinds of pearls, such as Chinese freshwater ... akoya oysters may get a bit of breathing room. Whether the cause is a natural virus, a ...

Only oysters of the Ostreidae family can make pearls, but many other types of mollusks can produce these gems, such as abalone and paua (New Zealand abalone), conchs, freshwater mussels ...

Illegal fishing of oyster pearls in the wild — natural pearls — is no longer a concern, mainly because they are so rare that it is not worth the effort. However, the pillage of freshwater ...

Pearls are made by marine oysters and freshwater mussels as a natural defence against an irritant such as a parasite entering their shell or damage to their fragile body. The oyster or mussel slowly ...