I’ve just read in a magazine about a new kind of robots called xenobots. They were created in an US lab by taking heart and skin stem cells from frogs (of the species Xenopus laevis) and assembling them into tiny robots (They mesure less than 1mm long) that can move. They can also execute simple tasks like walking or swimming and can live for at least a week without food.
However, they cannot reproduce or evolve. They are also biodegradable. They can also regenerate, like if you cut them open they will pull themselves together again like the T-1000 from Terminator 2. Future versions are going to heave ecological and medical uses, like collecting microplastics in the oceans, transporting medicine around the body or clean our arteries.
And heres a video about it: