Yes. They used to harvest it from dredges and such and used it to build a lot of roads along the gulf coast. I am sure that it is no longer used because of envionmental regulations now. Not sure what the past practices did to the eco system, but it had to have had an effect.
brings back memories. We had about a 500 yard long driveway into our place in Beaumont and about every 5 years, my dad would get a freah topping of oyster shell trucked-in.
I used to stand on it for hours hitting the oyster shells with an old wooden baseball bat