They trapped red grouper in a cage without a bottom; the fish dug out of it.

In the same way beavers construct DAMS, red grouper excavate and maintain distinct holes whose rocky surfaces provide a place for coral, sponges and other Marine life to congregate.

By building complex, three-dimensional structures that expose the hard rock beneath the sand, Miller said, red grouper create an environment in which seaweed, coral and sponges can thrive.