The third nipple was said to be the devil's mark, particularly when used to identify witches in the Salem Witch Trials and other witch hunts of the time.

Alleged witches were accused of suckling their familiars by this third nipple.

Often third nipples will be moles, warts or wens, and rarely will be an actual nipple with aureolae attached to milk ducts or breast tissue.

During the witch trials they were found almost anywhere on the torso, but obviously by definition are found around the chest area.