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 ...

and Oysters Clams and mussels are bivalve mollusks, or aquatic animals that have a two-part shell covering a soft body.

DESCRIPTION: Freshwater mussels are bivalve mollusks that have a two- valved hard shell, a soft body with respiratory, digestive and reproductive organs, and a muscular foot for locomotion, burrowing ...