Photos of the cottontails inspired nicknames like “Frankenstein bunnies,” “demon rabbits” and “zombie rabbits.”

Rabbits with black, hornlike spikes growing on their heads and other odd or unslightly protuberances are not dangerous and won't infect humans or other species, Colorado Parks and Wildlife said Wednesday, following days of social media posts about sightings of "Frankenstein bunnies," "demon rabbits" and "zombie rabbits" in and around Fort Collins.

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