An incredibly valuable experimental defensive weapon, the last known artifact of the ancient Taalo race. The Taalo's unusual silicon-based, mineral-like physiology somehow made their minds alone, of all members of the Sentient Milieu, immune to psychic compulsion from the Dnyarri conquerors. The pacifistic Taalo, unwilling to take up arms against their former friends, worked desperately to find an artificial method of imbuing this immunity into the minds of non-Taalo. Unfortunately, they were unable to develop such a device in time to stop the Dnyarri conquest, and when hordes of Dnyarri-controlled Ur-Quan invaded the surface of the Taalo homeworld, only one prototype Shield had been constructed before the Taalo's final disappearance. Captain Zelnick's research into the ancient Taalo allowed him to recover this device from the Taalo homeworld 20,000 years later, when it played a crucial role in the Second War.
The Taalo used technology similar to their own biology to build the Shield, which appears to the naked eye as a huge, glowing boulder. The subtlety and complexity of their engineering is staggering, outpacing even the genius of the Chenjesu. All human attempts to analyze the Shield show it to be nothing more than an apparently randomly mixed, undifferentiated lump of common minerals. However, its fluorescence by an unknown process, unaccounted for by any naturally fluorescing substances within the rock, as well as its regular shape and structure are clear signs that it is artificial. Its anti-psi abilities were discovered by accident; even in its quiescent state, any esper-capable human who approached it was plagued by headaches and mental confusion as the Shield warred against their natural, unconscious psychic probing. Experimentation discovered that running even a small electric current anywhere on the Shield's surface greatly multiplied this effect until all psi interaction in the Shield's vicinity was completely canceled, at least to the limits of measurements available by human methods.
This jury-rigged system was undoubtedly not the original intended use of the Shield, and this method of generating an anti-psi field was probably much weaker and less efficient than a fully completed Shield would have been. The neo-Dnyarri perceived this, and, realizing its psi abilities were amplified and refined enough to exert some influence even in the Shield's presence, was able to compel Zelnick to keep it in his protection, though it could not enslave him.