I thought I would throw out what I have learned to anybody new at this. On bull horns as in cattle bull horns they are made of layer after layer of keratin. It is just amazing how dense and hard it is. I have seen old pipe smokers with horn pipes that would glow red through the horn. I thought at the time how thin that was. Now I realize it was thin but incredibly durable and hard. You would think being that hard they would be brittle but that does not seem to be the case. The two middle horns have been sanded the one at the top and the horn on the bottom have not. That second horn from the top I have probably spent at least a hour and a half on. It is almost finished but I really ended up bearing down to get some of those scores out of it. That is with a wheel on the end of a drill. I am going to vibrate sand it next with 220 until it is smooth enough for steel wool. I am going to take jewelers rouge tripoli then blue to them with a drill and buffer when they get that smooth. Lot of sanding. I dont know about other animal horns but you can get the damage out of what I got if your willing to sand it. My skulls were pretty clean going in. They have been under water for a week so I pulled them out today. Dumped the clumps and kept about half the water and filled it up again. Those teech are in there so many different ways I was afraid if they fell out I might not be able to figure out what socket they went into so I built me a teath keeper with a milk carton I cut in half. It has pressure up on the teeth so maybe they wont fall out. Even if they do maybe they will at least stay with the right head.