“Oyster shells collected through the program[s] are placed back in North Carolina coastal waters to provide a place for baby oysters to attach and grow. Oysters are not just a food source for humans, birds and fish. They clean pollutants from the water. Oyster reefs also provide habitat for baby fish and other marine life. When oysters spawn, the larvae need a hard substrate on which to attach and grow. And oysters prefer to attach to shell material.
If you're interested in participating, there are plenty of oyster drop-off centers, run by the NCCF scattered around the state, and there might be one in your area!!
Here's the NCCF list of all of the oyster shell recycling locations across the state: Oyster Shell Recycling | North Carolina Coastal Federation. You can recycle other calcium-based shells, such as clams or mussels, too!