Answer:
Pearl.
Explanation:
A pearl is a hard, glistening object produced within the soft tissue of a living shelled mollusk or another animal, such as fossil conulariids. Just like the shell of a mollusk, a pearl is composed of calcium carbonate in minute crystalline form, which has deposited in concentric layers.
And it is a staple material to create earrings, bracelets and necklaces in it. + It comes from the giant clams.
