That's funny... after staring at the picture until my eyes were bugging out, I was swearing I was seeing a lobster-like tail at the bottom and some beady eyes on the top. Maybe even some very small claws? But then thought... nah... my eyes are just playing tricks on me.
First thought was Mantis Shrimp, but I wouldn't expect one to be out in the open like that. Probably just some species of lobster - there are a bunch of them.
that's a bumblebee shrimp. It is a reef safe carnivore. It usually eats the tube feet from sea stars but should eat prepared foods no problem. Unless you have one of the few reef safe sea stars or the asterina spp. You shouldn't see any problems.