Also known as a quantum phase inverter. The Tox Uthat was invented by Kal Dano in the twenty-seventh century. It is a palm-sized crystal capable of stopping the nuclear reaction going on within a star. Afraid that the Tox Uthat would be stolen, Dano traveled to the twenty-second century and hid in on the planet Risa. The Tox Uthat became a target of both twenty-seventh century criminals seeking to retrieve it, and twenty-fourth archaeologists who believed in what was regarded as a legendary device. Dr. Samuel Estragon in particular devoted half of his life to trying to locate the Tox Uthat. After he died in 2366, his assistant Vash carried on and succeed in locating the Uthat, but the Ferengi Sovak and two Vorgon felons from the twenty-seventh century also tried to obtain the device. Captain Picard, vacationing on Risa, became involved and eventually destroyed the Tox Uthat to keep it from any unethical persons.