They modelled it on polychaetes, or "paddle worms", which use tiny paddles on their body segments to push through sand, mud or water.

"We turned to biological inspiration because, in the peculiar environment of the gut, traditional forms of robotic locomotion don't work," says Arianna Menciassi. "Worms have locomotion systems suited to such unstructured, slippery environments."

But Gardner says the system would need careful testing. "If something this complicated goes wrong, it could be very hard to get out."

Movies, movies, movies.

And, previously.