A sea shell is a hard, protective outer layer of an animal that lives in the ocean. The three most common types of sea shells are the CONCH, TRITON, and COWRIE. The CONCH is a large spiral shell with a pointed end and can be found in warm waters. The TRITON is a large, heavy shell with a long spout and is found in tropical and subtropical waters. The COWRIE is a small, smooth shell with a glossy surface and is found in shallow waters.