Bonacon

A mythical animal in the form of a bull with horns wrapped inside, which defends itself from enemies by throwing scalding manure at them.

It is this feature that is reflected in almost all illustrations in medieval manuscripts and it is this feature that is the only mysterious detail in the appearance of this animal. The original description is taken from the "Natural History" Pliny the Elder:

It is said that in Peonia there is a wild animal called "bonas": its mane is like a horse, but otherwise it looks like a bull; the horns are bent back so much that they are unsuitable for battle, as a result of which bonas flees from danger, and defecates on the move, so that the manure covers sometimes the distance is up to three yugers, and touching it burns the pursuers, as if they are touching fire.