Qahsas were organically developed by the Yuuzhan Vong, functioning as a type of computer.
These organisms possessed the capability to retain the knowledge of the Yuuzhan Vong empire's Shapers, acting as biological memory repositories. Their sizes varied, ranging from compact individual devices to extensive databases for worldships. Access to a qahsa was achieved through a cognition hood. They could be cultivated rapidly on demand, with portable versions of the device available. A genetically encoded lock could be placed on the qahsa, permitting access only via a highly complex biochemical key.
The data within these organic computers was structured in increasingly complex layers of cortices, with each successive layer accessible only by a highly skilled individual. The Shaper caste maintained seven cortices, surrounding the ultimate eighth cortex. Master Shapers could access data beyond the fifth cortex, whereas Shaper Adepts were limited to the fifth. Functioning similarly to computers or memory banks, qahsas stored information about history, techniques, and past occurrences.
The Yuuzhan Vong believed that the data contained within a qahsa was a gift from Yun'o. Individuals who sought new information through innovation were branded as heretics.
Genetic splicers were the tools used to access them. A specific type of qahsa was the Qang qahsa, which housed the eight Shaping protocols.
During the Yuuzhan Vong War, Jedi Klin-Fa Gi and Bey Gandan sought to emulate Wurth Skidder's actions by masquerading as slaves. They were subsequently brought onto a Shaper vessel before the galaxy learned of the caste's existence. At that point, they were assigned to care for a living information system, a qahsa. As the Shaper sects worked on developing anti-Jedi weapons, they encoded data within a qahsa intended for delivery to Warmaster Tsavong Lah. It was then that Klin-Fa Gi and Bey Gandan sabotaged the ship, attempting to retrieve the qahsa. However, because it was genetically encoded, she could not open it, leading her to infiltrate Wayland in search of a method to unlock the biot.
Aboard the worldship Baanu Miir, Shaper Adept Nen Yim attempted to use the qahsa's knowledge to find a way to heal the dying Rikyam brain of the ancient vessel. However, she found that the knowledge was insufficient for the task and tried to consult the Qang Qahsa's database, only to discover that the Eighth Cortex was almost devoid of knowledge.
When Tahiri Veila, Nen Yim, Corran Horn, Harrar and Nom Anor traveled to Zonama Sekot in 28 ABY, Nen Yim brought a qahsa to gather information. The qahsas also held protocols in case Zonama Sekot proved dangerous. Nom Anor used these protocols in an attempt to destroy Zonama Sekot.
Nen Yim later utilized a qahsa during her investigation of the living planet Zonama Sekot. After examining the native life, she found many organisms similar to ancient Yuuzhan'tar, which was later confirmed by the presence of relatives of the lim tree, which were extinct, with only their blueprints remaining in the qahsas.
To test her theory about The Force, Nen Yim used a newly grown qahsa to connect her mind with Zonama Sekot, thus discovering its secret as a child of their ancient homeworld. She was killed for her knowledge by Yu'shaa, who was actually Nom Anor, who then used one of her qahsa's to unleash a replicative disease on Zonama Sekot to destroy it.