What is the world's largest living structure?

The Great Barrier Reef is the world’s largest living structure.

It is a vast coral reef ecosystem off the northeast coast of Australia, extending for about 2,300 kilometres along Queensland. The system includes thousands of individual reefs and hundreds of continental and coral islands.

The reef is built by colonies of tiny animals called coral polyps. Their calcium carbonate skeletons accumulate over generations, creating complex habitats for fish, turtles, molluscs, seabirds and many other species.

The Great Barrier Reef is not a single continuous wall. It is a network of reefs separated by channels and open water. It is also a UNESCO World Heritage Site and faces serious threats from marine heatwaves, coral bleaching, pollution and coastal development.