Broken tail
 

We have had one of our cats for over 8 years now. When we got him he was a baby. He had a huge knot in his tail. Apparently he had at some point broken it. He still has a bump there and if you run your hand over his tail you can feel it. It just adds character to his tail. I am sorry that he had to go through that but it has not really effected him since it has healed properly.