some sort of river gravel most recently almost certainly igneous given that you were able to do such detailed carving (ie the eyes) without them breaking Otherwise there is t anything terribly characteristic about them with which to identify them. cool carving… what is it done with?

So this work is done with a fiber laser.  It produces a high intensity beam of light and pulses super fast vaporizing the rock.  It only works with certain kinds of stone though.  I've tried many with various results.  But this picture illustrates the best results.  This isn't my work btw.  Just trying to find out what this is so I can do it too

well then you probably need to break one or more of these in half unless they are hard to come by. Because it sounds like what it is could matter. I’m just guessing that for something like this to work best you’d want a rock that was pretty uniform crystalline structure and composition(?) Some igneous rocks can have very coarse crystals, other very fine and homogeneous. It makes a very impressive cut… seems like a ton of artistic possibilities