Some cottontail rabbits in Fort Collins, Colorado, have been drawing attention because they have wart-like growths on their faces that look like horns.

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

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.