The Great Barrier Reef photographed from the International Space Station

The Great Barrier Reef photographed from the International Space Station

From the technological, human-made cocoon of the International Space Station, orbiting in the vast ocean of space, a view of the Great Barrier Reef off Australia’s east coast. The 133,000-square-mile reef is the largest structure on Earth that was made by living organisms. Tiny coral polyps secrete calcium carbonate to build the reef, creating a unique ecosystem for hundreds of other organisms, and they don’t charge rent to a single one.