When the Vivarium was discovered, Imogen Reed was tasked with studying the machine. The Vivarium generated the room it was located in on its screen then furniture then uploaded a scan of Reed herself which the WAU had stolen, at some point. Reed, in the virtual reality, collapsed. The real Reed panicked and intended to contain it which had the virtual Reed plead against the decision.
In Transmissions #8, a disoriented Reed remembers her studying of the machine. Though the power source was unknown, the Vivarium was really warm and more energetic as a person approached it. The machinery, corrupted by the WAU in a seemingly primitive manner, such as utilizing a loader piston recurve as parts, was actually a quite advanced artificial reality system.
Catherine Chun suspected that the WAU copied her early artificial reality capsules in the ARK project and both machines were quite similar except in one aspect: Chun's AR-capsule utilized conventional model neurographs produced from David Munshi's brain scan technology where the WAU's AR-capsule allowed a perfect copy to run unlimited. This thrust of development allowed Chun to replicate the WAU's method which officially spawned the ARK-project.