The Gambian pouched rat is a nocturnal pouched rat and is among the largest muroids in the world, growing up to about 0.9 metres (3 ft) long including the tail. It’s not a true rat, but rather a muroid rodent. Its name comes from the large, hamster-like pouches in its cheeks. A Tanzanian social enterprise founded by two Belgians, APOPO, trains Gambian pouched rats to detect land mines and tuberculosis with their highly developed sense of smell. The trained pouched rats are called HeroRATS. The rats are cheaper to train than mine-detecting dogs; a rat requires $7,300 for nine months of training, whereas a dog costs about $25,000 for training.