For nearly 40 years, a 350-foot-tall metal frame in the Gulf of Mexico supported a platform that pumped oil and gas from the seafloor. The 3,000-ton structure was recently converted into an artificial reef off the coast of Louisiana, where it will serve as habitat for fish and other marine life.

Shell’s Cougar platform was installed in 1981 and produced about 31 million barrels of oil and gas over its lifetime, said Shell external relations advisor, Theodore Rolfvondenbaumen. The platform was recently decommissioned and the deck and topside were brought back to shore. The metal frame of the structure was donated to Louisiana’s Artificial Reef Program.

The program provides marine habitat and benefits oil and gas companies by reducing the cost of barging the equipment back to shore. Shell has converted at least three platform jackets into artificial reefs, Rolfvondenbaumen said.

“Because of the important role offshore oil and gas structures play in supporting marine ecosystems and recreational fishing, we continue to look for opportunities to participate in artificial reefing programs,” he said. “However, we have also decided to return some of our assets to shore for cleaning and dismantling when we believe it is the safest method.”

Companies that participate in the program are required to donate half of their savings to Louisiana’s Artificial Reef Trust Fund. Shell donated $619,000, which will go toward maintaining and monitoring the Cougar reef.

The metal structures act like natural reefs by attracting organisms such as barnacles and bivalves, which colonize on them and, in turn, attract fish and other marine life, according to the Bureau of Safety and Environmental Enforcement.

There have been more than 7,000 offshore oil and gas platforms installed in the Gulf of Mexico, according to the Louisiana Department of Wildlife and Fisheries. Since 1973, 4,100 of these platforms have been decommissioned. Federal regulations require the removal of the structures within one year from the lease termination.

All five Gulf of Mexico coastal states — Alabama, Florida, Louisiana, Mississippi and Texas– have programs for converting oil and gas platforms into artificial reefs. BSEE officials said that as of January 2017, 515 platforms were converted to artificial reefs in the Gulf.

The majority of those artificial reefs have been built in Louisiana and Texas. That’s because the majority of oil and gas platforms are installed off the coast of the two states, according to the bureau website.

To convert the jacket into an artificial reef, Shell contracted a special heavy-lift vessel to move the metal structures about 50 miles from its original position to a site off the coast of Louisiana. The reef is already attracting reef-dependent fish, including red snapper and amberjack, a Shell news release states.