Ray, we used to have shell like that in a local lake. You could fill a box with the chinquapin(crackers) in short order. Sometimes 30, 40 boats. Big shell bed. But the cane fields dumped enough run off into the lake it covered the shell. That was 15 to 20 years ago. Well low and behold they are dredging the silt and trying to save the lake. Hope it is before I get to much older. lol