A new transforming turtle robot can explore treacherous regions where the land meets the sea--and may lead to future machines that navigate complex real-world conditions. Combining the best mobility features of an ocean-swimming turtle and a land-walking tortoise, the Amphibious Robotic Turtle (ART), described recently in Nature, can morph its limbs from turtlelike flippers to tortoiselike legs. "Most amphibious robots … use dedicated propulsion systems in each environment," says Yale University roboticist Rebecca Kramer-Bottiglio, who is the senior author on the paper. "Our system adapts a single unified propulsion mechanism for both environments: it has four limbs, and those limbs can transition between a flipper state for aquatic locomotion and a leg state for terrestrial locomotion." Each morphing limb is surrounded by a composite polymer material that is malleable when hot and stiff when cool.