In my earlier post about the unicorn, I completely forgot to mention the narwhal, the "unicorn of the sea". But the narwhal horn is no horn...it is an ivory tusk tooth that grows right through the upper lip. Now whether your an evolutionist or IDist, that's just outright strange in any camp. I can't imagine the selection pressure that would require this (other than possibly opening breathing holes in ice), nor can I imagine a reason the Grand Designer would design this.
Nevertheless, a true unicorn it ain't...horns are horns; teeth aren't horns. Besides, I can't imagine any virgin wanting a narwhal head resting in her lap!