The Waikiki Aquarium has maintained cultures of living corals since 1978 and now has the oldest and perhaps largest collection of living corals in the United States.
All corals begin as a single polyp.
Many types of corals grow by dividing. Two polyps, then four, then eight and so on until hundreds or thousands of polyps form large colonies. This is the image you are now viewing. If it is daytime in Hawaii you should see a brown polyp with a green center. The coral's mouth is a tiny hole in the center of the polyp.