Coral Creation is a term used to describe the formation of coral atolls and reefs. An ATOLL is a ring-shaped coral REEF, island, or chain of islands formed of coral. A REEF is a ridge of rocks or sand just above or below the surface of the water. Both atolls and reefs are formed by coral polyps, which are tiny animals that secrete calcium carbonate to form a hard skeleton. These structures provide habitats for many species of fish and other marine life.