Wired News: Lost Limb? Worm May Hold Answers: "Scientists have for the first time completed a survey of gene function in a highly regenerative species of worm that could offer important insights into cell regrowth in humans.

Putting the abilities of Wolverine in the movie X-Men to shame, a small piece of a planarian worm can regenerate an entire new body. The worm's ability to regenerate is so powerful that a tissue fragment only 1/279 of the worm's length can grow into a new animal."