- "Some say the coral implants ruin our slaves. Only the weak ones."
- ―Yuuzhan Vong slaver
Yorik-Kul, or surge-coral in Galactic Basic Standard, was an organic device used by the Yuuzhan Vong. Surge-coral was implanted into slaves, which would then allow the slave to receive mental commands from a yammosk or a dhuryam. This, however, came at a cost, since the wearers would eventually lose their sentience and become mindless beings. Slaves that had lost their minds were used as cannon fodder to absorb blaster fire on the battlefield. Surge-coral also caused its wearers to grow thin and vanish in the Force. Eventually, the Shapers developed surge-coral that was less detrimental to the slaves, which only caused pain instead of turning them into drones.
Jacen Solo was implanted with surge-coral after he was captured by the Yuuzhan Vong, which eventually allowed him to sense the Yuuzhan Vong through the Force. A'Sharad Hett was also the victim of said implantation during his own time as a captive of the Yuuzhan Vong. Years later, Hett, as Darth Krayt, was plagued and slowly being killed by the surge-coral's effects. Krayt was thus motivated to find and use Cade Skywalker to heal him of his implants.
By 127 ABY, Sith Lady Darth Maladi and Zenoc Quah of the One Sith had created a strain of Yorik-Kul that, after implanted, would grow when exposed to Force lightning, causing extreme pain and even death.
- Boba Fett: A Practical Man
- Star Wars: Invasion 8: Rescues, Part 3
- Dark Tide I: Onslaught (First appearance)
- Dark Tide II: Ruin
- Agents of Chaos II: Jedi Eclipse
- Balance Point (Mentioned only)
- Edge of Victory I: Conquest
- Emissary of the Void (Mentioned only)
- Star by Star (Mentioned only)
- Dark Journey (Indirect mention only)
- The Apprentice
- Enemy Lines I: Rebel Dream
- Destiny's Way
- The Unifying Force
- Star Wars: Legacy 15: Claws of the Dragon, Part 2
- Star Wars: Legacy 27: Into the Core (Mentioned only)
- Star Wars: Legacy 29: Vector, Part 10 (Indirect mention only)
- Star Wars: Legacy 30: Vector, Part 11 (Mentioned only)
- The New Jedi Order Sourcebook
- Ultimate Adversaries
- The New Essential Guide to Weapons and Technology
- The Complete Star Wars Encyclopedia (See coral restraining implant)