Weird historical artifact of the day: This is not a dog excrement, it's a T-1151 Dog Doo Transmitter from the collection of the National Museum of the US Air Force. It looks gross, but it was incredibly useful during the Vietnam War.
Developed by the United States military intelligence in the 1970s, the poop transmitter was a homing beacon. Here's an x-ray view of its interior:
The museum's description:
Dropped along the Ho Chi Minh trail by air, this device transmitted a warning when supply movements occurred during the night. The signals were monitored by a variety of agencies, including the CIA.
Gale Encyclopedia of Espionage & Intelligence:
At just over four inches long and three-quarters of an inch in height, this inconspicuous spy tool was small enough to be carried easily. It could send or receive radio messages, usually by Morse code. (...) Because the Doo transmitter was often left undisturbed, operational life was often a function of the battery life of its nickel-cadmium battery array. This advantage was often essential when the transmitter was utilized as a homing device. Because the device gave the appearance of fecal matter, it was often left undisturbed and thus a retained high efficiency as a homing beacon even when planted days or weeks before a mission. (via)