Mantis shrimp?

[ed99]

Folks,

I found this guy with my live rock. Fortunately he was strutting around on a rock at the top of my tank when I noticed him and I was able to get him in the sump. I think it is a mantis. Can anybody confirm and id? I'm guessing maybe a G. Smithii but I have no real idea. My pictures are not great. He is green with yellow spots with kind of a black outline to the spots