Its a rock, not sure what kind though. It seems to me that there is no way it happened naturally. Ive had people tell me it looks like Buddha and other people tell me its just a wierd rock.
It's a bit hard to tell without getting a closer look but to me it looks a lot like steatite that was used to sharpen auls(spelling?) or arrow shafts. I have a couple that I have found & it sure looks similar. Try looking up "shaft straightener".
The one I have has several of the grooves in it but yours has a few more. I would put money on it being a tool and not a natural stone.
Thanks for the info cruisin I researched what you said and it lead me to "sinew stones". Due to the size of the lines I believe that is what this is. However I am still confused on if the lines are at random or were they trying to produce a image?