A group of scientists backed by the US Navy is developing a robotic jellyfish that should, in theory, be able to power itself indefinitely, because it draws its fuel from the hydrogen in the water around it, the Telegraph reports. The so-called "robojelly" works a lot like real jellyfish, which propel themselves by opening their bodies with a single, central muscle, then snapping them closed again, pushing out any water inside.
The robotic version works much the same way. It's built of a shape-metal alloy that remembers its original shape even after being crunched down, and it's coated with platinum black powder, which generates heat and power by reacting with the hydrogen and oxygen in water. The only thing standing between robojelly and total undersea conquest? So far it only moves in one direction. (Read more research stories.)