Most famously, those who reach OT level III will learn about Xenu, the galactic tyrant who stacked hundreds of billions of his frozen victims around Earth's volcanoes 75 million years ago before blowing them up with hydrogen bombs and brainwashing them with a "three-D, super colossal motion picture" for 36 days. The traumatised thetans subsequently clustered around human bodies, in effect acting as invisible spiritual head lice that can only be removed using advanced Scientology techniques. Reportedly, the cost of reaching OT III approaches $360,000.