A Finger

One of these treasures was a simple tree branch. Upon first inspection, it looked no different from a random twig one might find in a dense forest, but that was only as long as it remained into its crystalline container. The moment it was taken out, it emitted such a rich natural and soothing energy that one would feel decades younger just being by it. 

This wasn't just any twig, it was one of the roots of the World Tree. With a piece of itself here, coupled with the rich Life Energy given off by the Life Stone, the World Tree succeeded to sustaining a projection of itself. 

The World Tree was filled with the natural energy that made Elves so great at beast taming and was linked to their absolute power.