Achilles' heel

Achilles' heel is a historical body part acquired by the Professor at an auction. It's a symbol for a deadly weakness.

Trivia

 * The heel we saw in "The Duh-Vinci Code" could have been preserved like many other body parts, such as the head. If this is true, we can assume it was somehow removed from . It's also possible that the Professor was ripped off, as Achilles is a mythological character.

Appearances

 * Debut: