The world's first living robots have been built using stem cells from frog embryos, in a strange machine-animal hybrid that scientists say is an "entirely new life-form".

A xenobot. Credit:University of Vermont

Dubbed "xenobots" because they are constructed of biological material taken from the Xenopus laevis frog, the little bots are the first to be constructed from living cells.

Researchers are hopeful they could be programmed to move through arteries scraping away plaque, or swim through oceans removing toxic microplastic. And because they are alive, they can replicate and repair themselves if damaged or torn.

"These are novel living machines," said Dr Joshua Bongard, a computer scientist and robotics expert at the University of Vermont, who co-led the new research. "They're neither a traditional robot nor a known species of animal. It's a new class of artefact: a living, programmable organism."