A conch is a marine gastropod or, more simply, a large sea snail. Conchs are valued for their meat, shell and non-nacreous pearls. Conch pearls are formed by concentric layers of fibrous calcium. This layering often produces a much-desired flame structure, which is characteristic of conch pearls. Because they are a calcareous concretion, the pearls have a porcelain finish and luster, very similar to the interior of the conch shell. Conch pearls are not cultured, but are usually found as a by-product as fishermen clean their catch for conch meat. The gems are usually baroque or oval in shape and generally a salmon-colored orange-pink.