When talking about corals, people normally refer to stony corals that build fascinating reefs. Actually, the term coral is much broader and refers to most of the animals in the class Anthozoa and a few animals in the class Hydrozoa of the Phylum Cnidaria. They are not movable. With their flora or tree like appearance, they are easily presumed to be plants under the sea. This book introduces different coral species and their growth form, the formation and distribution of coral reefs, and the importance of protecting corals.