When a thief improves what he's stolen and sells it or leaves the object to his heirs... the buyer acquires the right to that improvement. But what about if the thief is an idolator? Plus, what counts as an improvement? (With a palm tree as a case study) Also, a new mishnah, where the change to the animal is that it ages... or is reduced in value because of external reasons. Plus, the Gemara's discussion of aging leading to an increase in value.