This “AirJelly” floating mechanical creature is a joy to watch:

AirJelly houses two lithium-ion polymer accumulator batteries rated at 8 V and 400 mA, which can be completely charged in half an hour and are AirJelly’s sole source of power. A connected central electric drive unit transmits the force to a bevel gear wheel and then to eight spur gears in sequence. These gears power eight shafts, each of which activates a crank; these in turn move the jellyfish’s eight tentacles. Each tentacle is designed as a structure with Fin Ray Effect®- a construction derived from the functional anatomy of a fish’s fin. The actual structure consists of two alternating tension and pressure flanks movably connected by ribs. If a flank is subjected to pressure, the geometrical structure automatically bendsin the direction of the applied force. Together, the tentacles produce a peristaltic forward motion similar to that of their biological model.

AirJelly [French] [via]