Can anyone tell me what type of cactus this is? My son bought it when it was only 2 inches tall and it had a flower on it. It blooms little flowers every year for about a day and then the blooms fade away. It has got so tall and heavy that it will not stand up on its own now. I know I need to repot it? Not sure if I should repot it in a container that is long and let it lay on rocks, or just in a container like it is in now. Any help would be greatly appreciated.

