Viral photos have inspired a fluffle of unflattering nicknames, including "Frankenstein bunnies," "demon rabbits" and "zombie rabbits."

Colorado Parks and Wildlife: Scary-looking rabbits were hopping around Fort Collins. These weren’t your standard cute, fluffy bunnies; they had horn-like growths protruding from their faces and bodies.

The unsightly bunnies are infected with cottontail rabbit papillomavirus, which can cause growths that resemble warts or tentacles.