They were large animals that resembled mollusk-like works that were bioengineered to serve as a waste processor. This was accomplished by digging through all sorts of materials even metal and stone which was done so through a cap that contained several pincers. The chuk'a then moved through the rock as well as other material whereupon they ground up anything that was encountered after which they were consumed. The digested material was then excreted into a more recycled form of matter which was used in the construction of buildings and structures.
Tunnels were often formed by the passing of the chuk'a which was used to connect various underground chambers. When not needed, they were commanded to go to sleep which was very deep and required a complex set of stimulations in order to arouse the creature once again. If disturbed, then a potentially dangerous situation occurred as it was deadly to awaken a sleeping chuk'a.
A number of these creatures were released onto Coruscant where they began to aid their masters attempts at transforming the ecumenopolis into a copy of their long dead homeworld of Yuuzhan'tar. This involved the destruction of the deepest layers of metallic construction that existed below the planet's surface.
- The New Jedi Order: Force Heretic I: Remnant (First appearance)
- The New Jedi Order: The Unifying Force