Producing up to 500 million pounds of oysters each year, the Gulf Coast region of the United States is a shellfish haven: The area accounts for 67% of the oysters consumed in the U.S . But each oyster slurped down leaves behind a shell, and recycling those shells— instead of sending them to landfill —could actually be the key to rebuilding a coastal region decimated by natural and manmade disasters.

Last October, the Alabama Coastal Foundation (ACF), a nonprofit dedicating to protecting the state’s coastal environment, teamed up with the waste-management company Republic Services to launch an oyster-shell recycling program in the region. It began with just a few restaurants: A designated representative from Republic Services would drive out at 3 a.m. on Mondays, Wednesdays, and Fridays to collect shells left over by diners, and bring them to a nature preserve where they can aerate and “cure” for several months before being returned to the ocean. The program has since scaled up to 29 restaurants, and Mark Berte, the executive director of the ACF, tells Fast Company that interest keeps growing.

While it’s common practice among seafood restaurants to send their empty shells to landfill with the rest of their waste, a handful of regions are beginning to put the shells to more productive use by returning them to the ocean, where they become the building blocks of restored oyster beds.

For oysters to grow, they have to be able to attach to a firm substrate like rock. Along the Gulf Coast, oyster reefs form when young oysters attach to the left-behind shells of other oysters. But decades of over-harvesting, disease, and pollution have begun to decimate oyster reefs, 85% of which globally have disappeared. And in the Gulf region, disasters like the 2010 Deepwater Horizon oil spill have further wrecked the habitats.

By working with Republic Services to collect the discarded shells from restaurants, the ACF wants to contribute to the effort to revitalize the Gulf Coasts’ oyster reefs. In 2012, The Nature Conservancy (TNC) launched an effort to repair the Gulf region following the Deepwater Horizon spill, and as part of that has called for a $150 million investment in oyster-reef restoration, including the rebuilding of 100 miles of reefs. Doing so, TNC claims, will bring jobs to the region and ensure its shellfish industry will continue to thrive.

“The more shells they give us, the more oysters they can keep serving,” Berte says.