Aging oil rigs are saving the lives of countless fish, including overfished species that are making a comeback because juvenile fish use the rigs as a refuge. The Guardian reports that off the coast of Santa Barbara, California, there is a disused oil platform where marine biologists recently saw hundreds of thousands of juvenile rockfish finding shelter amid the hulking metal structure, alongside waving white anemones, clusters of mussels, and silver jack mackerel.

The seasoned marine biologists have been observing this remarkable spectacle for years. Holly, which was put out of use in 2015, is one of 27 oil rigs built off the coast of California decades ago that have become hotbeds of biological activity.

While not natural structures, their platforms have been embedded into the muddy seabed long enough to become part of the ocean environment, providing a home for creatures like mussels and barnacles, which in turn attract larger fish and sea lions that find safety and food there.