Robojelly is a biomimetic robot jellyfish designed for underwater surveillance and rescue, and while researchers have been working on it for quite some time a recent development might be its most innovative feature yet. The robot is now powered by hydrogen from the water it swims in, which reacts with platinum-coated carbon nanotubes on the flexible "muscles" to generate energy required for propulsion. The robot uses a jellyfish (Aurelia aurita)-inspired bell design in the first place because of its high level of energy efficiency — as the bell contracts and relaxes, it expels water to propel the body. With the new hydrogen-powered design, the robot could theoretically operate without ever running out of energy.