The best-known sources of pearls are marine mollusks, especially the pearl oysters, conchs and abalone found worldwide. Each species has a unique form, ecology and history.
Mollusks first evolved 530 million years ago, and fossil pearls have been found in several extinct species. Some of the most unusual natural pearls today--pink conch pearls from the Queen Conch, blue-green pearls from abalone and orange melo pearls from Baler Shells--are produced by marine snails. Humans have long harvested these and other marine mollusks for their mother-of-pearl shells and natural pearls. Today many species of mollusks are raised in pearl culturing, also called "perliculture," producing cultured pearls in a wide range of shapes, sizes and colors.