At the bottom of the sea, we often find large reefs with corals attached to them. These are "coral reefs", the so-called "tropical forests" of the seas. For the formation of corals and consequently reefs, light and temperature of the sun are very important. The reef is a hospitable environment for many species of fish and marine mammals, as they can easily find food, as well as a hiding place to protect themselves from predators. There are three types of coral reefs: the "marginal reefs", which grow on rocky shores, the "coral dams", farther from the shore, and the "atolls", coral islands submerged in the great depths of the oceans.