The substance was an element with unusual properties which allowed it to generate anti-matter energy when it was bombarded by certain particles. The resultant power produced gravity waves as well as other forms of energy. It was believed that Elerium-115 was not naturally found within the Sol system and it could not be reproduced. Alien spacecraft made use of this energy source in their power cores which generated anti-matter energy as well as gravity waves and other forms of useful energy. The conversion of matter to energy with these power cores was with an incredible 99% efficiency which meant only a small quantity of Elerium-115 was needed.