Photos of the many kinds of coral in the ocean around Indonesia.
Corals are marine invertebrates — yes, they are animals, not plants — within the class Anthozoa of the phylum Cnidaria. They typically live in compact colonies of many identical individual polyps. Hard corals include the important reef builders that inhabit tropical oceans and secrete calcium carbonate to form a hard skeleton (but not all "hard" corals are rigid). (from Wikipedia, thank you)
Hard CoralSoft Coral