Living robots grown from stem cells and designed by a computer have begun to multiply, scientists have said, is a milestone that might lead to self-replicating machines.

In the year 2020, researchers in the United States programmed a supercomputer to generate blueprints for totally new species using virtual skin and heart cells, which they subsequently produced in the actual world.

The "xenobots," which are minuscule animal-machine hybrids, were able to move on their own and stay "alive" for weeks because of their embryonic energy stores.

Scientists have discovered that when "xenobots" are put in a petri dish with embryonic frog stem cells, the bots scoop the cells up into small circular mounds that change into new animals and move.

Kinematic replication had previously been observed in molecular machinery, but not at higher levels of life. Splitting, budding, or giving birth are the most common ways for multicellular creatures to reproduce.

Organisms look like Pac-Man
Following their discovery that the bots could reproduce, the researchers returned to their computer to create a better form for reproduction, finally creating an organism that resembled Pac-Man, a 1980s arcade game.

Using microscopic forceps, the robots are constructed from living cells.

The "c-shaped" parents were videoed gathering the cells in their "mouths" before constructing the "offspring" from the loose cells in a completely new mode of biological reproduction unlike any animal or plant known to science.

Professor Michael Levin of Tufts University in Massachusetts told CNN that he was "astounded" by it.

“Frogs have a way of reproducing that they normally use but when you ... liberate (the cells) from the rest of the embryo and you give them a chance to figure out how to be in a new environment, not only do they figure out a new way to move, but they also figure out apparently a new way to reproduce.”

Xenobots may be able to assist in the clearing of arteries

A team of researchers used small forceps and a little electric knife to cut and combine stem cells collected from African frog embryos under a microscope into a near approximation of the shapes described by the computer, based on the blueprints.

Once assembled into forms never seen in nature, the cells began to work together. The skin cells formed a "body" while contracting heart muscle cells were repurposed to create a forward motion, allowing the robots to move on their own.

Researchers are hopeful the xenobots could one day be programmed to move through arteries scraping away plaque or swim through oceans removing toxic microplastic.

And now it is proven they can replicate, they could repair themselves if damaged or torn, scientists hope.