The growths are most likely caused by a summertime virus common in some U.S. states, but wildlife officials say there is no risk of transmission to humans or other animals.

As weird and concerning as they appear, the virus that causes the dark, wart-like horns or tentacles to grow on cottontail rabbits is relatively common and usually not anything to worry about, CPW

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.