I. Importance A. Basic structure Built of skeletons of tiny marine invertebrate organisms. Animals themselves tiny, but calcium carbonate skeletons build up and can be extremely strong.
Corals die, but reef remains.
Many organisms add to reef structure including algae, molluscs, sponges and worms. Algae extremely important. While reefs can last for millions of years, the living surface is extremely fragile and easily damaged. B. Value Tourism. Reefs are beautiful and interesting.