Colorful Coral Reef with Tropical Fish

Though coral reefs often form impressive architectures on their own, this one had a little human help. It's built on a cube-shaped frame structure sunk off the coast of Owase, Japan, to provide extra surface area for coral growth and attract marine life. Not every such coral kickstarter has been beneficial for the ocean: Over the centuries since ancient Romans and Persians began creating artificial reefs, some have been built from questionable materials like car tires. Implemented responsibly, though, these structures are important tools in marine conservation efforts worldwide.