The AM stone is engraved on all sides. But for now, let's take a peek at Side "A".
There is quite a handful of info here -- so much, I'm not even going to try and point it all out. For now we'll look at several different images of the same side, as different lighting (and yes -- imaging) reveals more.
Let's first take notice at this figure located in the upper center of the stone. The image below primarily shows the head of what appears to be a spirit being.
Note the shape of the head. And the possible ears, or horns, whatever.
I believe that the entire stone itself was modified into an effigy. Possibly an effigy of the figurehead below.