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.

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

Rabbits spotted with "tentacles" or horns growing out of their heads. But it's really happened in Colorado. "There are really rabbits with what look like tentacles growing out of them," USA Today reported.