Not sure where this goes but if u place a spike wall in front of them and when their health is low enough they have to turn into a ball and be stuck in a constant cycle until the spike wall is removed. It's a great way if you find one and want to tame it later. Unless it gets killed by something else while in a ball it should be fine. I stil have one stuck on one of my walls and ima keep it ther until I can tame it for stones.