Marine Biology- Immortal Worms

Scientists have been studying a particular (planarian) worms limitless ability to regenerate and replace aged or damaged tissues or cells, thus becoming potentially immortal. They can regenerate new muscle, skin, or even an entire brain, over and over again. This may be a possible breakthrough in alleviating the aging process of human cells.

More: http://www.macroevolution.net/planarians.html#.T67TlMVaKSo