AKA Spy Cat

Acoustic Kitty
The idea was to have a cat – placed in particular locations like window sills, park benches, or dustbins – record sounds from its surroundings that would then be transmitted back to C.I.A. operatives.

The agents involved believed that trained cats would go where they heard interesting sounds – because apparently the cats would find conversations between Soviet officials interesting. Due to their inconspicuous nature, the cats would go unnoticed as they passed by while recording the sounds, so the reasoning went.

The C.I.A. recruited a veterinary surgeon to perform an hour-long procedure on a test cat. He implanted a small radio transmitter on the back of the cat’s neck, a microphone into its ear canal, and a nearly invisible wire across its fur that connected the two devices. Former C.I.A. officer Victor Marchetti put it a little more bluntly: “They slit the cat open, put batteries in him, wired him up.”

https://allthatsinteresting.com/acoustic-