For a long time, people have debated the origin of teratomas, the so-named “monster tumors” that contain all sorts of well-formed tissues.
Aristotle attributed teratomas to hair which had been swallowed by the patient and deposited in various body tissues. Other theories were more ominous for the patient: teratomas were variously reported to be a consequence of sexual relations with the devil, an expression of a nightmare (incubus), evidence of engagement in witchcraft, or a punishment for wickedness. Geez. I’m glad I didn’t live in the Middle Ages.
Anyway. Here is an article from the New York Times describing how these tumors are now being used for research in the war against cancer. Cool!