What are coral reefs, and how do they form?

Answer: Coral reefs are underwater structures made of calcium carbonate, secreted by colonies of marine invertebrates called corals. They are formed when coral larvae called planulae settle on hard surfaces in shallow, warm waters. The larvae develop into individual coral polyps, which grow and secrete calcium carbonate to form an exoskeleton. As polyps reproduce and grow, they form colonies and continue to build the framework of the coral reef. A symbiotic relationship between coral polyps and microscopic algae, zooxanthellae, plays a crucial role in providing nutrients and energy to the coral, facilitating the growth and formation of coral reefs. Coral reefs are considered one of the most biodiverse ecosystems on Earth, providing habitats for countless marine species and various benefits for humans.