Reef producing coral are called hermatypic. Coral reefs are made by coral polyps as they cover sheets of calcium carbonate under their frames. The corals that form reefs are reef producing corals. They build reefs by putting hard calcareous material for their bones, making the firm structure of the reef. Corals belong to the animal kingdom and are members of the phylum Cnidaria. The coral animal is like a sea anemone which has a soft body and tentacles.
