At a conference in Germany, engineers unveiled a robotic jellyfish designed to swim—but not sting—like the real thing.

The AquaJelly runs on rechargeable lithium-ion batteries, has a roughly spherical body and uses eight tentacles to get around in the water. The tentacles undulate like the tail of a real fish, and small fins at the ends give the machine a little extra push on the water. To steer, the robot shifts its weight, and it drives around its tank autonomously.

When General Motors rolled out its "skateboard" vision for a fuel cell car at the 2002 Detroit auto show in January, there was buzz, and there was a big question. The skateboard concept, called Auto-nomy, was the product of GM's Design and Technology Fusion Group, and it radically reordered automobile physiology: Fuel cells, hydrogen, motor, and brakes were all crammed into a 15-foot-long, 6-inch-thick chassis onto which modular car bodies could be snapped. Drive-by-wire controls would plug into the skateboard's computer brain through a docking port.

The automobile has been on the verge of being reinvented practically since it was invented. Cars that would float and fly, cars that would walk, cars that would cruise like bubble-shaped VIP lounges: Surely a brand-new car was right around the corner, or at least a couple of years away. Problem was, the irreducible requirements of engine, transmission, suspension, and fuel tank, and all the mechanical linkages involved (pedal to throttle, driveshaft to wheels), dictated much about not only how a car would function, but how it would look.