What are reef producing coral called? what is the coral reef composed of? how are they created

Reef producing coral are called hermatypic corals or hard corals or stony corals. They are the primary reef-building corals.

Composition:

Exoskeleton of coral reefs is composed of calcium carbonate (CaCO₃) which support and protect the corals in ocean.

Formation:

Coral reefs are made up of soft tiny animals called polyps which belong to the family of anemones and jellyfish. These polyps are present in large number from hundreds to thousands in a coral.The lower portion of polyp secretes a hard skeleton of limestone (calcium carbonate) which helps in protection and support or attachment to the substratum in ocean like rocks or lower old skeletons of polyps.

volcanoes (an event in the geosphere) release a large amount of particulate matter into the atmosphere. these particles serve as nuclei for the formation of water droplets (hydrosphere). rainfall (hydrosphere) often increases following an eruption, stimulating plant growth (biosphere).