The Great Barrier Reef formed from a long and slow process involving the accumulation of organic materials, such as stone, plants and animals and shells of dead corals. The Great Barrier Reef started forming approximately 20 million years ago. Dead shells from coral, along with remains from algae, anemones, fish, worms, crustaceans, snails, turtles and snakes accumulated and gave shape to the Great Barrier Reef as well.
Historians lack consensus on when people first discovered the Great Barrier Reef. According to historical records, however, Aborigines likely discovered the Great Barrier Reef approximately 40,000 years ago. Aborigines settled on the lands of modern-day Australia at that time. They fished in the surrounding waters and navigated through the treacherous channels of nearby Torres Strait. At that time, however, the Great Barrier Reef looked much different. It covered large tracts of dry land shaped as coastal plains.
Historians understand more about the Great Barrier Reef because of the introduction of Europeans to the Australian continent. Sailors and explorers reported ships striking land below the water, necessitating costly and time-consuming repairs. Through trial and error, Europeans eventually discovered safe navigational routes through and around the Great Barrier Reef. The Great Barrier Reef claimed the lives on more than 30 ships through the years and remains a central fishing area.