 The exotics, who have fled their home galaxy because of religious persecution, were marooned on Pliocene Earth when their "living" ship crashed on earth.The Tanu and Firvulag exotics have metapsychic powers and are extremely long-lived.The Tanu use a torc-like device to bring their wide variety of latent metapsychic abilities into a partial operancy, while the Firvulag are naturally operant metapsychics – who have a limited range of abilities compared to the Tanu.