A retractable foot, a siphon for sucking up water, powerful muscles, and, sometimes, a pearl ... and mussels, clams are bivalves, a kind of mollusk that's encased in a shell made of two valves ...

Oysters are the primary producers of pearls, clams and mussels can also create ... Oysters are bivalves that means their shell is composed of two valves connected by an elastic ligament.

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 ...

Pearls are the result of a mollusc's reaction to irritants such as parasites that enter its shell. Although model pearls are perfectly round and smooth, in reality they come in a huge number of shapes ...