This prototype surgical microrobot, "Cleo", is about 3.5 CM on each side and is small enough to fit inside the colon of an adult. Tiny antennae detect obstacles, a claw can grasp and carry objects and it has tilt sensors. Surgeons can control Cleo with a joystick or navigate under its own guidance. Future versions, hardened against the hostile chemical environment of the human body, might be able to perform surgical tasks such as polyp removal. Cleo was designed by James McLurkin at MIT.