The coral reef teems with life. Coral reefs provided fishes with food and shelter, supporting a thriving ecosystem. Corals are colonies of tiny animals. Each animal is called a polyp (say, "PAH-lip"). The skeletons of these coral colonies are immense, forming small mountains on the floor of the ocean. These mountains are called coral heads. This coral head is made up of several different types of corals. You can see corals growing in balls, long tubes, leafy bushes, and other shapes. The coral makes a foundation for other creatures, like sponges and anemones. Fishes, stingrays, worms, and other invertebrates make their homes in the holes and crevaces of the coral head.
In the background you can see another coral head. Underwater, visibility is limited by plankton in the water. Between the coral heads, you can see a small patch of sand. This pattern of coral heads separated by canyons of sand is called a "spur and groove" reef. The coral heads are the "spurs," and the sand canyons are the "grooves." Stingrays hide in these sand canyons.