In 2019, Australia lowered a 58-ton concrete greenhouse into the Great Barrier Reef; the 12-metre underwater structure became a living artwork and coral habitat

In John Brewer Reef, off the coast of Townsville, Australia, exists a greenhouse with no windows, no door, and no street address you could put on an envelope to send a postcard to. To visit this particular greenhouse, you'd need a boat, an oxygen tank, and be prepared to dive into the Coral Sea around 55 feet below sea level. There, resting inside the natural harbor lies a 12 meters tall concrete structure weighing around 58 tons, inside which there are two dozen human-sized figurines, based on real schoolchildren, tending to a bunch of trays full of corals as if participating in an odd science fair experiment.