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.