Details: This poster is of Coral Shell I, by Donna Geissler. It shows shells and coral.
A seashell, also known as a sea shell, or simply as a shell, is the common name for a hard, protective outer layer, a shell, that was created by a sea creature, a marine organism. The shell is part of the body of a marine animal. In most cases a shell is an exoskeleton, usually that of an animal without a backbone, an invertebrate. Seashells are most often found on beaches.