“The Thing aka the Great Seal Bug. On 4th August, 1945, a group of Soviet school children presented to W. Averell Harriman (The US Ambassador to the USSR) with a carved US Seal as gesture of friendship. It hung in his office for 7 years before discovering it contained a listening device.”

“It was a very clever device, a passive cavity resonator. It had a tiny antenna and a membrane that vibrated with voice sounds. When the Soviets sent a radio signal toward it, the vibrating membrane modulated the signal, allowing the Soviets to hear what was being said. But because it had no power source of its own and did not transmit on its own, it was nearly impossible to detect with conventional radio sweep equipment of that era.

It was discovered accidentally by a British radio operator listening to a Soviet radio frequency, where he heard American conversations. He realized that American conversations were being transmitted to the Soviets. Following the lead, American experts looked for the source of the transmission and found it in the Seal.”