What are seashells made of?
Seashells are, quite simply, the exoskeletons of mollusks. At Britannica.com, we learned a good deal about the composition of seashells, including the three distinct substances involved: an outer layer of the horny substance conchiolin, an intermediate layer of calcite, and a smooth inner layer composed mainly of calcium carbonate. But how does a mollusk actually create a shell? An article from Earth & Sky explains:The blood of a mollusk is rich in a liquid form of calcium. A soft, outer organ called the mantle concentrates the calcium in areas where it can separate out from the blood, forming calcium carbonate crystals. The mantle deposits sheets of the crystal in varying thicknesses. The individual crystals in each layer vary in shape and orientation. A fasinating new field called
