British scientists, ever eager to regain the mad science mantle, have built a robot that is a) soft and b) eats things.
According to New Scientist, it's a "Soft robot with a mouth and gut [that] can forage for its own food".
The Mail sees it quite clearly: "Robotics experts has developed a soft robot capable of consuming organic material for energy, effectively creating a machine which digests living things."
Yes, we can get technical, but you get the idea:
By opening its “mouth”, made from a soft polymer membrane, the robot can suck in a belly full of water and biomatter. The artificial gut – a microbial fuel cell (MFC) – is filled with greedy microbes that break down the biomass and convert its chemical energy into electrical energy, which powers the robot. Digested waste matter is then expelled out the rear end, just as more water is sucked in the front for the next feed.
And this is how it becomes a threat to humanity: "With every mouthful, the robot’s reserves are replenished, so in theory it could roam indefinitely." Oh yes.
(thanks to Jesse "The Last Human to be Devoured" Walker)