An Eyetooth 

Martin Jones, an  Englishman, went blind in one eye. So, doctors pulled out a living eyetooth canine out of his mouth and implanted into his eye. Strange, huh? Well, this is gross: Then they took a piece of flesh and put it on the tooth. The doctors then cut a hole in the cornea, permitting light to seep in. This very procedure gave 600 people sight! Click here to see the picture: http://www.interestingfacts.org/fact/tooth-implanted-into-his-eyeweeblylink_new_window (I wouldn't look at it if I didn't have to...)