Terrigen Crystal

A Terrigen Crystal is Kree work, and its purpose is to finish something the Kree started. More than five thousand years ago a rogue faction of them ran genetic experiments across the universe, trying to raise an army out of other species by writing a latent gene into a host that would grant a single physical ability. The gene does nothing on its own. It needs Terrigenesis, and Terrigenesis needs the mist a Terrigen Crystal gives off. Every world they tried came to nothing. Earth was the exception: the human population there proved far more receptive than anything else the Kree had found, and they built a city under what is now Puerto Rico to work from. The crystals are kept inside containment devices called Diviners, which open at the touch of an altered subject and are lethal to anyone else who handles them.