They were relatives of the yammosk war coordinators but were far larger and much more powerful as their duties entailed them with running all the organisms of an entire planet making them world coordinators. At least thirteen such creatures were bred and were irreplaceable as they were trained with a single task which was to be fulfilled which in turn led them into becoming the pazhkic Yuuzhan'tar al'tirrna, or World Brain.
One of them would manage the thousands of biological processes that go into terraforming and maintaining Yuuzhan'tar, the Yuuzhan Vong homeworld. Because the World Brain must be of the highest quality, it was selected through a special process called the tizo'pil Yun'tchilat: the Day of Comprehending the Will of the Gods. All thirteen dhuryams were severed from their telepathic link with their slaves by the Shreeyam'tiz, which were a smaller sub-species of the yammosk that existed only for that task. When one dhuryam remained, from either killing its siblings or by some other method, it assumed direct control over Yuuzhan'tar.
The World Brain was chosen by Jacen Solo after he killed all twelve of the other dhuryams. Jacen convinced it to sabotage the Vongforming of Coruscant. As the war came to its closing stages, dhuryam governor brains were becoming increasingly scarce for the Yuuzhan Vong Empire.
The dhuryam remained after the Liberation of Coruscant.
Years later, the dhuryam would again help Jacen Solo. During the Second Galactic Civil War, Solo was appointed the leader of the Galactic Alliance Guard. He covertly used the World Brain to detect and round up Corellian insurgents on Coruscant. When Alema Rar returned to Coruscant to exact revenge on the Solo family, she followed Jacen to the World Brain. When she attempted to kill him with a blowdart, Lumiya, Jacen's Sith mentor, Force pushed him out of the way of Alema's attack and the dart instead hit the World Brain. The World Brain began to thrash violently. Jacen and Lumiya then began an attempt to save the World Brain. Unfortunately, the World Brain succumbed to the toxins and Jacen was upset by the loss of his friend.
- Traitor (First appearance)
- Destiny's Way (Mentioned only)
- Force Heretic I: Remnant (Mentioned only)
- Force Heretic III: Reunion (Mentioned only)
- The Final Prophecy (Mentioned only)
- The Unifying Force
- Bloodlines (Mentioned only)
- Tempest(Mentioned only)
- Fury (Mentioned only)