Ooh! I just thought... Burrow blocks could spawn other animals than gophers occasionally. While they spawn actual gophers usually, you may get a badger on unlucky days. Badgers are aggressive, and they will attack you. If you injure them enough, they will run back to their burrow just like gophers, but they are aggressive until then. Badgers would be the same size as gophers (one block), but black and white instead of all brown.