Wraithbone is essentially solidified warp energy which is manipulated by a Bonesinger into any shape that is required. It is stronger than any known plasteel and harder to damage than adamantium, and will naturally repair itself, though the process can be sped up by a Bonesinger. Being created from the warp, Wraithbone has innate psychic abilities allowing it to be used as a communications pathway as well as structural support. It carries psychic energy much as a cable carrying current does, as well as containing psychic shields to protect the occupants from the warp.
Wraithbone effectively performs all of the tasks a machine would. The organic members of the crew use psychic powers to perform their duties, but it is the wraithbone itself that actually does it. In the case of Eldar ships, the basic framework is created from Wraithbone and then the internal areas are made, finishing with the actual internal components. Even the mighty Craftworlds are made of Wraithbone, and this is how the occupants of craftworlds survived the birth of Slaanesh, for the psychic shield of the Wraithbone protected them from his mighty psychic scream.
Wraithbone emits a sympathetic psychic signal that Eldar can lock onto and use to control the object. Generally, Eldar buildings have a flowing form and lack any harsh angles. It is also used to make Eldar Runes.
- Codex: Eldar (4th Edition), pg. 13