whats the best kind of sea urchin to get

[DEAD_BY_DAWN]

well after finally putting some snails in my tank i was glad to see that the moray didnt show any interest in them,on the other hand the birdmouth wrasse loved picking them up and smashing them against the lr,not the best $6.00 ive ever spent but atleast the the birdmouth is happy,so no crabs no snails what about a urchin any ideas on what ones would survive ,or any other ideas for a cleanup crew ?.