Wraithbone is a Warp-based material used by the Eldar. Wraithbone is a very durable, lightweight material that is easily manipulated and shaped using psionic power. Eldar artisans specialized in the manipulation of this material are known as bonesingers.
Wraithbone is essentially solidified warp energy which is manipulated by a bonesinger into whatever is needed. It can only be shaped by using psychic powers, but it is extremely malleable and can be made into any shape the bonesinger wants. It is also very tough and resilient. Being created from the warp, it has innate psychic attributes, allowing it to be used as a communications pathway as well as a structural material. It carries psychic energy much as a cable carries current. It can also generate psychic fields to protect occupants from the warp .
In the case of Eldar ships, the basic framework is created from wraithbone; then the internal areas are made, finishing with the actual internal components. Effectively, wraithbone performs all of the tasks of machinery and electronics. The crew use psychic powers to perform their duties, but the wraithbone itself actually executes their orders. Even Craftworlds are made of wraithbone, and this is how the occupants of craftworlds survived the birth of Slaanesh: the psychic shield of the wraithbone protected them from the psychic scream of Slaanesh's birth.
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.
Wraithbone is also used to make Eldar runes.
- Codex: Eldar (4th Edition), page 13