The Barasonilash are a sentient Xenos species of four-armed bipeds with short legs, six eyes and a gill-like slit in place of a nose. Their existence may also predate the origins of the Aeldari, making them possibly among the oldest sentient species known to exist.
This theory was concocted by the Rogue Trader and Xenologist Janus Draik, who discovered the Barasonilash were referenced in both Aeldari and Imperial sources. These include several translated ancient Aeldari myths and legends that refer to wars and events that predate their own origins, while the Imperial Xenographia Universalis contains reports of Adeptus Mechanicus Explorator Fleets that encountered Barasonilash Seers. Given the similarity in the description given of the Barasonilash in both Aeldari and Imperial sources, Draik is inclined to believe they are the same species. However if this is true, the Barasonilash may have since gone extinct, as Draik has been unable to find recent records of any encounters with the species.