Has anyone heard or seen in their LFS a crystal rock that looks like a block or chunks of ice? I was wondering what it is exactly. I had a friend who had it in the tank and it desolved. I know that the Big Al's stores carry them I haven't checked the website to see if they have them there but I was just wondering if anyone knows anything about them and what they really are, what they are made up of especially if they are going to desolve in the tank.