Bog mummies (also called peat mummies or mire mummies) rarely, if ever, leave their marshy realms. Less powerful than their more notorious artificially preserved kin, bog mummies are preserved not by agents introduced during rituals but by the natural elements present in the airless, acidic morass of a peat bog or muddy swamp. While corpses preserved in this manner can certainly rise from the mire as bog mummies as the result of a curse by fell powers or the directed influence of a necromancer, the vast majority of them animate from a seething need for vengeance or to pursue some dire agenda left unfinished at the time of death-often because the creature was slain or otherwise betrayed. The nature of tthis emotional tie to life and the emotional power of the deceased compel unlife beyond death, while the preservative qualities of the bog within which the body was disposed of does the rest.