The coelom is an essential feature of many animals, including vertebrates, annelids and molluscs. This body cavity performs many functions, including acting as a cushion for internal organs, allowing movement and flexibility, and providing a space for the development of eggs and sperm. Synonyms for the coelom include body cavity, peritoneum, and visceral cavity. The term "septom" is also sometimes used to refer specifically to the division of the coelom into compartments by septa. While the term coelom is relatively specific to the anatomy of certain types of animals, understanding its structure and functions is essential to studying comparative anatomy, evolution, and physiology.