The U.S. Department of the Interior has rules governing nonproducing ocean oil rigs: They must be torn down after a certain period of time. What sounds like a sensible policy to deter oil companies from abandoning idle rigs is now being reconsidered as the growing depletion of natural reefs may give them a new purpose as artificial reefs.

Below the surface at one 30-year-old rig in the Gulf of Mexico, corals, sea fans and sponges cover a maze of pipes. Schools of jack and snapper, solitary grouper and barracuda circle in its shadows and eco-dive boats periodically stop at the enormous structure, where dolphins, sea turtles and sharks are often spotted.

The New York Times reports that about 650 such oil and gas industry relics, referred to as “idle iron”, would be demolished with large amounts of explosives under the old rules, killing thousands of fish and other sea creatures. Now the Gulf of Mexico Fishery Management Council is seeking recognition of offshore platforms as essential fish habitats. To ease liability concerns and help insure and maintain structures to be spared such removal, John Hoffman, chief executive of Black Elk Energy, an oil and gas company based in Houston, Texas, has founded a nonprofit organization, Save the Blue.

To convert a platform into a reef, approval is required by the Interior Department’s Bureau of Safety and Environmental Enforcement. Under the federal Rigs-to-Reefs program, a structure is only partially removed: cut off down to 85 feet below the water surface. Fish densities have been found to be 20 to 50 times higher near converted rigs than in open water. Each platform typically supports more than 10,000 fish.