The chemical compound CaCO3. A common natural form is the mineral calcite. The part of a church in which the main or only altar is found. Clasts are often recemented together to form a breccia. A marine invertebrate with a soft body and a hard external structure composed of calcium carbonate.
Corals live attached to the seafloor, especially in shallow, tropical seas.
Some corals live as separate individuals, others are colonial and form extensive reefs. The layers are known as courses. The layering of sediment that is inclined at an angle to the horizontal. A mid-Paleozoic period of geologic time. It began about 408 million years ago and lasted until about 360 million years ago.