origin of the pearls

 Oysters make pearls as a natural defense mechanism against irritants such as parasites entering their shell or damage to their fragile body. The formation of a pearl starts when a foreign substance slips into the oyster between the mantle and shell. This irritation causes the oyster to attempt to protect itself, producing nacre to cover the foreign substance. Over time, these layers form a pearl. Pearls are made by marine oysters and freshwater mussels, and they slowly secrete layers of aragonite and conchiolin, materials that also make up their shell. This creates a material called nacre, also known as mother-of-pearl, which encases the irritant and protects the mollusk from it