This robotic fish is not the first of its kind, but it’s certainly one of the coolest out there (granted, not too many of these actually exist). Developed by the Faculty of Engineering at Osaka City University, the unnamed robo fish can move very realistically and has a key selling point: It can be powered by a solid-polymer fuel cell dubbed “Power Tube”.

The fish, which is 10cm long, can not only swim around but also dive and rise, thanks to a joint at the front end. The developers first used a motor but scrapped that idea later when they found out power consumption stood at 1W. A magnet system then did the trick, pushing down that number to just 10 milliwatts. The final goal is to develop a robot fish that’s able to swim for three consecutive days on a single charge.

The robot is intended to be used for rescue work and maritime research in the future.

This video shows the robot fish (and another cool model) in action: