The Malacology is the science that studies the mollusks. The shells are biological and rigid structures that protect and support the soft-bodied animals without skeletons. They are composed of calcium carbonate (CaCO3) and are composed of three layers: the outer (periostracum), the median (ostracum), the inner (ipostracum).
The different colours are determined by the substances produced by mollusks in the formation of the shell. The different ornamentations are given by different intensities of secretion of calcium carbonate. The shell is derived from the secretion made by the mantle, a fold of skin that covers the mollusks’body.