Updated by: Arabinda Naik
According to Sir John Murray mounds are formed upon the sea bottom by deposition of limestone skeletons of many animals (such as shells of molluscs and starfish and deep-sea corals) when they reach about 50 fathoms, the corals grow on them and reach the water surface. A barrier reef results at the outer edge and an atoll is produced by the dissolution of the inner coral rocks. The mound ultimately became flattened like plateau.