It's not a skeleton. I'd say it's a Chaplain (but why blue?) and it's not his skull we're seeing, but his skull-shaped helmet.
I like the general idea, but it turned out a little funny, because the marine's neck is waaay to long :)
That Ork has either been holding that guy forever or likes a bit of skeleton beating...:D. And I didn't know Space Marines had such strong skeletons...
I think this mini would benefit from a better picture, more highlightd and maybe some work on the skeleton...something weird about it. :/