Got this at HD. My slow dial up has been frustrating in trying to id it online.
I have Dial-Up also,,,,What a pain, huh?
Your picture looked like a 'Cactiburre Cuctus' variety...
I don't think it is a cactus, but a mesemb that makes a good impersonation of a cactus. I'll look up the name when I come home.
I believe it is a Trichodiadema, maybe T. densum. See link below.
Here is a link that might be useful: Trichodiadema