Abersyn symbiotes, a species, survived by consuming the brain stem of sentient species. To maintain their dormant state, they required feeding into a plasma furnace. However, consistent exposure to a plasma vent also achieved the same result. These creatures were notorious for causing the death of numerous historical empires. Consequently, possession of an Abersyn symbiote was prohibited by Imperial law.
While Chelli Lona Aphra was a doctoral candidate at the University of Bar'leth, she dedicated her time to studying and exploring the planet Boothi XII, hoping to make a groundbreaking discovery. After her fruitless search on Boothi XII, Aphra's doctoral advisor, Toob-Nix, revealed to her a complete nest of Abersyn symbiotes within his private quarters. He explained his profound dislike for her and his refusal to grant her doctoral approval. In retaliation, Aphra, aided by Sana Starros, pilfered the entire nest and fabricated evidence to suggest she had discovered the Abersyn symbiotes on Boothi XII. As dictated by Imperial procedure, the symbiotes were immediately incinerated.
On Ktath'atn, the planet's Queen was an Abersyn symbiote entity that had taken control of a humanoid through Force drain. She maintained several members of her species to control her collection. She attempted to use them on Aphra and Luke Skywalker as a deceptive "dessert," but her plan failed when Aphra recognized the deception and fled with the Padawan. Later, Aphra located a sizable colony of the symbiotes. 0-0-0 directly implanted one into Krrsantan in order to make him go into a frenzy and attack the Queen's followers.