They look like a grey rhinoceros beast from Africa. Their horn contains a violently explosive fluid and anything touched by that fluid will explode, even other Erumpents, which is why the species quite rare. They possess a thick, charm-repellent hide and a long tail, rope-like in appearance.

Female Erumpents give birth to one calf at a time and their horn, tail and fluid are used as potion ingredients, though they are defined as a Class B Tradeable Material — Dangerous and Subject to Strict Controls. Like rhinoceroses they will not attack unless sorely provoked.