Pliny the Elder described the Bonnachon in his 1st-century Natural History as a cow like a creature with a horse’s mane and in turned horns. The Bonnachon habitat was the desert and grasslands of Asia. If a traveller passing were to encounter one it was not the Bonnachon horns that would not be the terrifying thing but the animal propensity for ejecting a great load of dung from its rear end that the ground would be for more than two acres. The Bonnachon dung was acrid and would burn through trees, plants, people and animals that were in the area of the Bonnachon dung.
John and Caitlin Matthews, The Element Encyclopaedia of Magical Creatures, 2013, Bonnachon, p 70