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.

Duke University engineers think they've made an important step towards developing robotic surgeons that operate independently. The robot they used in their experiments—which were just feasibility studies, and were not performed on real people—uses 3-D ultrasound as its eyes, and an AI program that processes the 3-D information it gathers to determine the robot's next steps.