Stony corals (or simply scleractinians) are the corals mainly in charge of placing the building blocks of, and accumulating, reef structures. Huge reef structures are produced when every single stony coral organism (polyp) that produces a framework of calcium carbonate. Coral Reef formed slowly as the condition of the water stabilizes and as the colony grows in numbers.
The majority of stony corals have really small polyps, about 1 to 3 millimeters (0.04 to 0.12 inches) in diameter, but overall colonies can mature very big and weigh quite a few tons. These types of colonies are comprised of millions of polyps that cultivate atop the limestone remains of previous colonies, ultimately creating enormous reefs.
Generally, massive corals are likely to grow gradually, growing in size from 0.5 to 2 centimeters (0.2 to 0.8 inches) each year. Nevertheless, under ideal circumstances (plenty of light, regular temperature, average wave action), a few varieties can develop around 4.5 centimeters annually.