Coral can be found in tropical ocean waters around the world. Today we learned about Australia's Great Barrier Reef. It is off the coast of Queensland in northeastern Australia, is the largest living thing on Earth and even visible from outer space! The 134,634 square mile ecosystem comprises thousands of reefs and hundreds of islands made of over 600 types of hard and soft coral. It's home to countless species of colorful fish, molluscs, starfish, turtles, dolphins and sharks.