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Coral reefs are vast underwater ecosystems built by colonies of tiny animals called coral polyps. are often to as the " of sea" due to incredible biodiversity. habitats, found in , clear, waters, food and shelter for approximately a quarter all marine species. The structure of the reef protects coastlines from storms and erosion by reducing wave energy. The health of coral reefs is vital for the overall balance of the ocean's ecosystem and for communities that depend on them.