Coral reefs are often referred to as the "rainforests of the sea" due to their high levels of biodiversity and complexity, similar to the tropical rainforests found on land. Just like rainforests, coral reefs support a wide variety of species and provide crucial ecosystem services such as food, protection, and habitat for marine life. Additionally, coral reefs are incredibly productive ecosystems, supporting a large number of marine species in a relatively small area, similar to the dense biodiversity found in rainforests.