Atoll
the name applied by geologists and others to any one of the lagoon islands, or annular coral reefs found in the Pacific and the Indian Oceans, the Red Sea, and some other parts of the the Pacific and the Indian Oceans, the oval rather than circular in form. On the top of the coral rock, which rises but slightly above the sea-level, is vegethe top of the coral rock, which rises but slightly above the sea-level, is vegeof white sand, exterior to which is a line of breakers. The ring of land, which is of white sand, exterior to which is a line of breakers. The ring of land, which is generally two or three breaks in the ring, affording ship channels into the lagenerally two or three breaks in the ring, affording ship channels into the laing land into the sea, prevented the coral animals, which are marine, from locating themselves or building.