Those are rock teeth. See at 3:50 how he's able to just press down smoothly on the rock and it splits. The pointed teeth allow for that better than traditional teeth would.
Gnarly material but, nice skills, yo. You must dream of moving a few thousand tons of sand once in a while. And then, when you are loading a thousands of tons of sand, you must dream of something a little more challenging and rocky... And so the sinusoidal function goes...