The vitalicron was used by the Yallow Fellowship, a cult which venerated the dark side of the Force, to contain the memories of an individual cultist. It was shaped like a truncated icosahedron, with a raised circle on each facet, and was colored blue-grey. The device had a genetic seal to secure its contents.
Used by the Yallow Fellowship, the vitalicron was kept at the Yallow Shrine on Mount Bikja amidst a store of artifacts which also included a Yallow soothsaber. By around 241 BBY, the Fellowship was long-extinct. The Jedi Padawan Klias Teradine, a proud and arrogant apprentice, discovered the location of the sanctum and persuaded his friend Tylera Yorrick to explore it with him, hoping to discover lost knowledge which would impress their Jedi Masters.
Yorrick, however, retained doubts. When the two entered the shrine, they were nearly killed by several booby traps, although Teradine was undeterred. The duo eventually found the cache of artifacts which included the vitalicron. Spotting the device, Teradine picked it up and explained its use to Yorrick, stating that their Masters would be impressed if they returned such a device. Yorrick, however, disagreed, arguing that not only was stealing morally wrong as the device did not belong to them, the shrine and its artifacts were also extremely dangerous, so they should be left where they were.
As they argued, Teradine was surprised when the vitalicron's genetic seal suddenly unlocked. He was overwhelmed by the device's contents, and dropped it as he collapsed to the floor. Yorrick asked him what was wrong, and Teradine, his eyes turning completely white, shouted for her to run. Disregarding the instruction, Yorrick stayed and attempted to assist Teradine, encouraging him to fight off the possession. However, the memories from the vitalicron took him over and he attacked her, engaging her in a lightsaber duel while insinuating that what had happened to him was somehow her fault. The duel ended when Yorrick killed Teradine in self-defense. In the aftermath, Yorrick departed the Jedi Order, becoming the mercenary Ty Yorrick, while Teradine's fate was covered up, such that later generations speculated he had been expelled from the Jedi for other reasons.
The vitalicron first appeared in the new Star Wars canon in the third issue of the 2021 IDW Publishing miniseries Star Wars: The High Republic Adventures — The Monster of Temple Peak, written by Cavan Scott and published on October 27, 2021. Vitalicrons originated in the Star Wars Legends continuity, where they first appeared in BioWare's 2011 massively multiplayer online role-playing video game Star Wars: The Old Republic. In Star Wars Legends, vitalicrons were used by the Voss to store the memories and visions of those that went through the healing practices of the Voss Mystics.