This guy is very cool: amazing behavior, very active and a good cleaner. Not considered quite reef safe but has been tolerant to soft corals I have. I enjoyed having him for a month now together with a bunch of shrimp and other small inverts.
Freeze dried krill is his favorite. Eats from my (clean/glowed) hand too. Otherwise he finds any non-living organic matter in the tank. He explores a lot.
Oh, BTW: he eats bristle worms. He might have exterminated the whole population in my tank. Very efficient.
There is the purple reef lobster, which belongs to real lobsters. It is also reef safe. The problem I have experienced is that they don't do well in small tanks where water parameters vary too much. Besides they hide most of the time, night and day. They are not very active at all.
The spiny lobster is evolutionary quite far form real lobsters (with enlarged claws). All the problems with purple lobsters listed above don't exist with these guys. They are, however, not totally reef safe (even though my polyps of all kinds are doing just fine). They may also grow pretty big in nature (in captivity their growth is retarded).