"Rayu" refers to lightning and its physical manifestations. Those who have been struck by lightning are often called "rayun purita" ("struck by lightning") or "purita" ("arrived"). It is these "purita" who have been called to become "yatiri". In their healing ceremonies, "yatiri" interact with (among other things) "achachilas" and "ruwitus". "Achachilas" are ancestors different from biological ancestors, and "ruwitus" are human skulls that are considered to be dead elders in either a generational or a cultural sense. "Ch'amakani" ("someone who has or owns the darkness") is an elder "yatiri" who undertakes the training of an apprentice "yatiri"-to-be.