In 1945 Soviet school children gave the US Ambassador to Moscow a gift. a large hand-carved wooden replica of the Great Seal of the United States. a gesture of friendship between wartime allies. The Ambassador hung it in his study at the embassy. It stayed there for seven years. Inside it was a listening device. No battery, power source or any active electronics. nothing that any counterintelligence sweep of the era could detect. because there was nothing to detect. It was called The Thing. Here's how it worked. The KGB would park outside the embassy or sit in a nearby building with a directional radio transmitter. They would aim a microwave beam at the Great Seal. The beam would activate a tiny resonant cavity inside the carving. The cavity would pick up voices in the room and modulate the reflected signal back to the receiver. A skilled operator would decode that reflection into clear audio. The principle that was invented, a passive cavity resonator that activates when hit by an external radio signal and reflects data back, is the basis of modern RFID technology. The chip in your work badge. the tag on your clothes. The contactless payment on your phone. All descended from a listening device built by a prisoner in a Soviet labor camp.