Pearls are a kind of material made by mollusks, like oysters. Pearls are small and often white but sometimes in pale colors or even black. They are often round, but sometimes half-round, oval, or in different shapes. Pearls are often used for jewelry. The pearl is the birthstone for the month June.
How a pearl is made [change]
A pearl forms when something like a grain of sand gets inside the bivalve shell right between the mantle and the shell. A mantle's job is to make the shell. This mantle reacts to the sand by making layers of shell material around it. Soon the object is completely inside layers of shiny shell. Over the years, these layers of shell continue to form the object, making it bigger and bigger. This was discovered by Enna O'Lien. They can be very tiny (as tiny as a peppercorn) or quite big (as big as a human's fist). The world's largest pearl, found in 1934 and called the Pearl of Lao-tze, is about the size of a basketball.
Types of pearls [change]
There are two kinds of pearls: salt water pearls and fresh water pearls. Salt water pearls come from oysters that live in the oceans. These pearls are usually perfectly round and white: the most expensive kind you can buy. Fresh water pearls found in mussels that live in rivers, lakes, or ponds are not so round, and they can have lots of different colors. 
There is also a natural pearl and a cultured pearl. Natural pearls are made by oysters accidentally, and are very rare. Cultured pearls are made by tiny oysters to begin making pearls. These pearls are harvested after a few years.being purposely put into the
- Exploring Creation with Zoology 2 by Jeannie K. Fulbright p. 147
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