Coral reefs are often considered as rocks, stones or plants on the bottom of the sea, but Coral is actually composed of calcareous skeletons of small animals called coral polyps, when a coral dies, it leaves its skeleton coral limestone behind young corals then themselves attach to the old skeleton and the cycle begins again. Coral reefs are generally found in tropical shallow waters near the equator, the shallow water is ideal for corals to survive as they need to sunlight.