Reef Balls

Coral reefs, they say, are the rainforests of the ocean. They're important linchpins of the ecosystem, they're delicate, and they take forever to make.

Unless, of course, you just press them up in a factory. Reef balls–concrete structures that support coral growth and provide habitats for all sorts of underwater life–seem to be working pretty well. Here's a Wall Street Journal story and here's the Reef Ball Foundation.