In a tiny laboratory pond, a robotic stingray flaps its fins and swims around. Roughly the width of a dime, the bot dashes distances multiple times its body size. It easily navigates around corners ...

It’s a bizarre sight: With a short burst of light, a sponge-shaped robot scoots across a tiled surface. Flipped on its back, it repeatedly twitches as if doing sit-ups. By tinkering with the light’s ...