The term 'SEASHELL' is an 8-letter crossword solution for the phrase 'THE SHELL OF A MARINE ORGANISM'. A seashell is a hard, protective outer layer that is secreted by many marine organisms, such as mollusks and crustaceans. It is often used as a form of defense against predators, and can also be used to help the organism float in the water. Seashells are often found washed up on beaches, and are popularly collected by beachgoers.