Coral reefs are primarily composed of calcium carbonate, which is secreted by reef-building corals.

Hard corals, belonging to the order Scleractinia, are the primary reef-builders, forming the structural framework of coral reefs.

Corals and microscopic algae, known as zooxanthellae, engage in a mutualistic relationship. The algae provide the coral with nutrients through photosynthesis, while the coral offers protection and a stable environment for the algae.

Calcification is the process by which corals use calcium and carbonate ions from seawater to form their calcium carbonate skeletons.

Sunlight is essential for coral reefs as it provides the energy required for photosynthesis by the symbiotic algae living within the coral tissues.

Accretion refers to the process by which coral reefs grow and expand over time through the accumulation of coral skeletons and other reef-building materials.

Atolls are circular or oval-shaped coral reefs with a central lagoon. They are typically found in the open ocean, far from land.

Coral bleaching occurs when corals expel the symbiotic algae living within their tissues, resulting in a loss of color and increased susceptibility to stress and disease.

Climate change, particularly rising sea temperatures, is a major contributor to coral bleaching and reef degradation.

Paleoclimatology is the study of past climates and environments using geological and biological evidence, such as coral reefs, to reconstruct ancient climate conditions.

Coral reefs provide valuable information about past climates by recording changes in sea level, preserving ancient marine organisms, and indicating past ocean temperatures.

Fringing reefs are long, narrow coral reefs that run parallel to the shoreline and are directly attached to the coast.

Erosion refers to the process by which coral reefs are broken down and worn away by physical forces such as waves, currents, and storms.

Barrier reefs are large, flat coral reefs with a shallow lagoon separated from the open ocean by a reef crest.

Patch reefs are small, isolated coral reefs that are not connected to a larger reef system and are typically found in deeper waters.