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A Waxy Tree Frog rests on a zookeeper's hand during a photocall to promote London Zoo's annual stock take of animals on January 4, 2012 in London, England.

New research has shown that microscopic life-forms made of frogs’ stem cells can self-replicate in a way not seen in other animals or plants.

Per The Washington Post, these xenobots, named after the African frog Xenopus laevis from which they are made, could move around, display collective behavior and heal themselves.

A study released Monday (November 29) suggests that the cell clumps also can be engineered to sustain themselves for at least five generations.

“There’s nothing theoretical that would stop us from making these out of human cells,” said Sam Kriegman, an author of the study published in the journal Proceedings of the National Academy of Sciences (PNAS). “They could perform useful work inside of human bodies in places were traditional robots can’t go because our bodies detest even the smallest amount of metal.”

Kriegman said the xenobots aren’t usable yet, but could lead to technology capable of corralling microplastic from the ocean into a retrievable ball or delivering medicine to a specific spot in a person’s body.

The finding that xenobots can reproduce is the latest result of research that began in 2018. The researchers took stem cells from the skin of frog embryos and put them in salt water, where they clumped together and enable the organisms to move.

The scientists noticed that the xenobots were swimming around randomly and would spontaneously make piles out of particles placed in the dish. One of the biologists started to wonder whether the tiny robots would do the same thing with individual stem cells, and it worked.

“Once he did that and showed us the video, there was a definitely a record scratch,” Kriegman said. “The first thing we thought of was robots building robots, which has been a dream of robotics since the very beginning.”

Xenobots straddle an unusual line between living organisms and robots since they are made of stem cells and can reproduce, but can move on their own and perform physical labor. Although most robots are made of metal, they are defined but by what they can do, not their material. Before now, Kriegman said, “no one has been using living materials as self-moving, self-powered robots.”

The researchers hope that the xenobots can help them better understand the process of replication and how to control it. Faced with a world full of self-replicating problems, such as the novel coronavirus and forest fires, Kriegman said studying xenobots could lead scientists closer to solutions.

The next step in the research is trying to build similar living robots out of mammal cells with a goal of eventually creating robots that can act without human oversight. “If we start to create these things to be more and more intelligent,” Kriegman said, “at some point, there needs to be additional ethical considerations.”

To those unnerved by the idea of reproducing robots, Kriegman said only a fragile set of easily changeable circumstances leads the xenobots to self-replicate. “If you change the amount of sodium in that water to be too high or too low, they’ll die,” he said. “If there’s a piece of copper in the dish, they’ll all die. It’s an extremely controllable and stoppable and safe system.”