When I was a kid my Grandpa used to take me out in S. GA looking for something he called powder rocks. I don't have any pictures but they came in various sizes and were a rough texture with a brownish color to them. When we picked them up and shook them we could hear the powder inside moving around. When we busted them open they would have various colored powder inside, mostly red or blue from what I remember. Does anybody know the actual name of these rocks or has anyone else found them?