The cavern beast was an unusual creature created by the Yuuzhan Vong.
The beast was an organism that was fixed in a location. Its huge mouth, which appeared to be nothing more than a lichen-covered cavern, was actually a type of stomach for the creature. A telepathic lure, making a person appear to be in trouble in the minds of others, drew animals and sentients into the cavern beast's mouth.
Once prey was inside, peristaltic contractions forced it into specialized stomachs, where it was held. The creature obtained nutrients and elements from the wastes of its captives, and their collective body heat regulated the beast's internal temperature. It fed captives by secreting fatty substances into stalactites inside the cavern that were edible and nutritious. When the cavern beast required food, it used a form of peristalsis to force captives into the digestive chamber, where they were assimilated into the body system.
The Yuuzhan Vong avoided these creatures, and one individual believed that the cavern beast was some kind of ancestor of the worldships.
At least one specimen of this species was present on the terraformed Coruscant when it fell to the Yuuzhan Vong empire. This creature grew in the deepest part of the changing city. It lured many captives into its mouth and served as a shelter for the survivors of the city from the Yuuzhan Vong who lived inside the cavern beast. In return for shelter, they sacrificed one of their own to the creature for digestion, their policy being the latest victim of the telepathic lure was the first to be sacrificed.
Jacen Solo fell prey to the cavern beast when he saved a teenage girl that was sacrificed by the inhabitants of the cave. After saving her, the people inside the cavern beast, which included the young girl, turned on him and tried to sacrifice Jacen. In anger, he implanted a suggestion in the primitive mind of the cavern beast that all members of the New Republic were poisonous. The creature then vomited its prey out of its orifice, after which it closed its teeth, preventing them from returning.
The expelled survivors were angry with Jacen, as they believed he destroyed their only shelter from the Yuuzhan Vong.