What is a characteristic of coral reefs?

Coral reefs are known for their rich biodiversity, serving as habitats for a wide variety of marine life, including fish, invertebrates, and other organisms. They are formed by colonies of tiny coral polyps that secrete calcium carbonate, which builds up over time to create the reef structure. Additionally, coral reefs are sensitive to environmental changes, making them vulnerable to threats such as climate change, pollution, and ocean acidification. Their complex ecosystems provide essential services, including coastal protection and supporting fisheries.