Even if they aren't mutated into teenage ninjas, turtles might one day be a viable alternative to drones for espionage and surveillance. They come already armor-plated, they're amphibious, they're powered by plants, and thanks to their natural desire to avoid obstacles, researchers have found a clever way to even make them remote controllable.
As demonstrated in this video, a large shield mounted to a turtle's shell can be remotely spun to make it think there's an obstacle to the left or right of it. And instinctively it goes in the opposite direction to avoid it, allowing someone at the controls to effectively steer it remotely.
Of course this setup is a little clunky—and a little conspicuous—to be used in the field. But sensor-laden surveillance turtles, or other animals, could one day be released into dangerous areas wearing tiny LCD shutter goggles instead that simulate obstacles in their field of view allowing them to be controlled just like a drone. And with the addition of mini katanas and tiny nunchaku, we may be able to replace our fighting forces altogether.