Corals are invertebrate marine animals of the Anthozoa class, Cnidaria. Typically, they live in compact colonies made up of a lot of polyps. Polyps are joined together by calcareous channels. After their death, another one is added to the old calcareous skeleton. That's how coral reefs form. The buco-anal opening of each individual is surrounded by 8 tentacles.
The limestone skeleton, named in Romanian, is a red or white most common color. It is used by people, especially for the production of objects of art and ornaments.
