Polyps need warm, shallow, sea water to grow, so coral reefs are often near land. There are three main types of reefs. A fringing reef is attached to the shore. An atoll is a ring of coral formed around a sunken volcano. A barrier reef has a channel of water between it and the shore. Although all types of coral polyps grow in similar ways, the many different polyps form more than 2,500 different kinds of coral! It may resemble tree branches, the human brain, tiny pipes, fans, feathers, lace, or mushrooms. It may be bright pink, glowing orange, rich purple, or brilliant yellow. The warm, sunlit water and many hiding places of a coral reef attract thousands of different animals. Students learn more about the creatures who live in a coral reef and then use their imagination to create their own diorama using ideas like these.