No idea what it is. It doesn't seem to be a Mantis, though.
My advice would be to put some heavy-duty gloves on (in case it actually is a mantis) and take that guy out. Put him in a cup and take some more pictures as well.
sw65galma on here has a mantis that he keeps that looks exactly like that.
I dont know how to link it but reefiness did a "Help!!Mantis Shrimp" thread on 2-21-06 where there is a pic of sw's mantis. Looks alot like your pic.
Can anyone who knows how to link it help me out
It looks stuck... if so your lucky. Dont turn off that jet, get a net and place it over the jet and then use a toothpick to pry it out so that it gets shot into the net. good luck!