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 ...

Oysters are the primary producers of pearls ... leading to pearl formation. Natural pearls vary in size, with those exceeding 10 millimetres being rare and particularly valuable.

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.

Throughout much of recorded history, a natural pearl necklace ... the shape and lustre of saltwater pearls, which they discovered while opening oysters for food. No matter the origin, a reverence ...

“They’re natural filters of water ... be used only for restoration testing — not human consumption or pearls. Oysters to help clean ocean water in a test project would be placed in small ...