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

A rapidly spreading virus is causing cottontail rabbits to grow black, tentacle-like growths out of their heads, prompting warnings to steer clear of the mutated animals.

Colorado Parks and Wildlife said the growths are caused by a virus and though unsightly pose little health risk to wild rabbits and no risk to humans.