I was enjoying some very fresh seafood on Cape Cod when a nearby sign beckoned me to recycle my oyster shells. I did not have any, but I thought the concept was very interesting. I had no idea that oyster shells could even be recycled. I have since learned that that they indeed can be. There is even an organized effort to return oyster shells (sans the recently-eaten oyster) back to the ocean they are dried and aged for about a year. This is vastly superior to sending them to a landfill.
According to the Massachusetts Oyster Project, the idea is to essentially put oyster shell back into what was their native habitats. The recycled shells have chemical properties that benefit the habitats of their oceans, particularly having to do with lessening levels of acidification in the water. As extra materials on a reef, they also help build protect the shoreline by strengthening the underwater barriers that lessen the wave energy from incoming water. In addition to providing places for young oysters to grow, they also provide space for different species to live underwater. These include fish, shrimp, crab, eels, mollusks, etc.
The program has been running since 2010.