The Tox Uthat (2366).
The Tox Uthat, also known as a quantum phase inhibitor, is a device that is able to stop the fusion process of a star. It was invented in the 27th century by Kal Dano, who hid it on planet Risa in the 22nd century to prevent it from being stolen by Vorgon criminals.
By the 24th century, the history of the Uthat had passed into local legend. A Federation archaeologist, Samuel Estragon, and his assistant Vash took an interest in finding the Uthat. After Dr. Estragon's death in the 2360s, Vash carried on the search, with financial backing from Estragon's sometimes associate, a Ferengi named Sovak. However, Vash betrayed Sovak and came to Risa without him.
In 2366, Vash found the Uthat buried in a cave on Risa, and subsequently threw Sovak off her trail with the assistance of Captain Jean-Luc Picard. Picard destroyed the Uthat using Transporter Code 14, to prevent it from falling into the wrong hands. (TNG: "Captain's Holiday")
- According to Q's Guide to the Continuum, Q says that the Vorgons would not have been a threat even if they had gotten their hands on the device; that in almost every possible reality where they found it, they ended up blowing themselves up with it. But then, Q does have a very strange sense of humor.
- The Tox Uthat is very similar to the weapon developed by Tolian Soran in Star Trek: Generations and probably works on the same operational principle.