What the researcher couldn't see was that the shells — obtained from restaurants and seafood plants — were attracting microorganisms. These covered the shells in what's called a biofilm, which is created when bacteria, algae, and single-celled organisms latch onto a surface. Finally, the shells themselves became a place for baby oysters to latch and grow. A single oyster can also filter 50 gallons of water a day, making the surrounding water cleaner for other sea life, including underwater plants, to flourish. Ocean life within the Gulf of Mexico is being restored in a way that makes it pretty clear that the place for the shells left behind after your seafood dinner isn't the trash — it's the ocean.