Way too kewl, I have a Black onyx one I found here in Peterborough Ont. that has a side veiw of a face, don't know if it's natural or man made as I can't see any marks on it. Yours definetly looks Alien and Man made. Nice find.
The skull represent three entrances. I have found alien type stuff before and it does make you wonder. When it comes to faces, we see them because our brain is hardwired to see faces. We are a unique animal as we can recognize faces. Faces are a minor part of a trail, I put a very low priority on them. They would more lilely identify who was there, not what is there.