Mad-Eye Moody's eye

A fake eye belonging to Alastor 'Mad-Eye' Moody, the enchanted device had an electric blue iris and could rotate 360 degrees in the wearer's head. The eye was able to see through anything, including the back of Moody's own head and even invisibility cloaks, and was the reason that Moody became known as 'Mad-Eye.' Useful for its defensive properties, the eye was valuable to others who wished for the extra level of protection, but ultimately it only functioned properly for its rightful owner.