Mine-detecting rats! (Evidently, they're not heavy enough to set off the mines...but they can smell them out!)
From the website:
HeroRATS are trained sniffer rats that detect explosives and screen for disease. This unusual idea has been developed into a competitive technology by a group of Belgian and Tanzanian researchers and animal trainers under the umbrella organization called APOPO. APOPO was initiated in response to the global landmine problem. In the mid 90's it was well recognized that most mine clearance techniques in use were slow, expensive, and dependant on foreign expertise.
Bart Weetjens, the founder of APOPO, got his first experience with rats as his childhood pets. Years later he remembered his pet rats when he became discouraged by the scourge of landmines in African countries and the expensive, time consuming, and foreign technologies available to clear them from the land. With their terrific sense of smell and trainability, rats could provide a cheaper, more efficient and locally available means to detect landmines. These would be HeroRATS.
Through partnerships with Antwerp University and Sokoine University of Agriculture, Bart set up laboratories in Belgium and Tanzania to begin training and testing African Giant Pouched Rats in the detection of explosive materials. Bart’s hunch about rats proved correct and the trainings were a tremendous success.HeroRATS can use their highly sensitive and accurate sense of smell to identify the presence of both metal and plastic cased landmines, and can be trained to detect a number of different things like explosives, tuberculosis bacteria, tobacco, contraband, etc.
Working with the Geneva International Center for Humanitarian Demining (GICHD), accreditation standards have been established to license the mine-detecting HeroRATS and over 30 trained HeroRATS are now working to demine Mozambique. From these beginnings, APOPO has also expanded its HeroRAT programs to detect Tuberculosis. Further uses are being explored, such as the ability to conduct search and rescue operations in rubble after disasters.