Principle purpose of this lecture is to present on Beauty of Reefs. Coral reefs are often called the “rainforests of the sea” due to the great diversity of creatures that form them. Note that the brilliant colours apparent in corals are from the microscopic algae in the coral tissues (different colours absorb different wavelengths of light). Reefs are natural structures of rock formed by marine animals. Today’s reefs are largely made by corals, but in the geological past, have been constructed by sponges and bizarre clams. Reef-building organisms build skeletons of calcium carbonate in the form of aragonite or calcite.