[159] Elerium-115 is the gold-colored material that powers UFOs and other alien technologies in X-COM: UFO Defense. In the case of UFO power sources, it comes in plug-shaped energy units - which is essentially what the Elerium colliders used to power NXE's EVAs are.

[926] Actually, it dates back to an earlier incarnation of the bureau, back in the days when X-COM was a purely military force.