Xenobots are cells that form new roles beyond their original biological function—for example, using hairlike cilia for locomotion rather than transporting mucus. Because they appear to reassemble into this new form and function, the authors argue that xenobots form a kind of “third state” of life, wherein cells can reorganize after the death of an organism to form something new. These forms likely wouldn’t materialize in nature, but xenobots show that cells have a surprising ability to adapt to changes in their environment. Experiments with human cells, or “anthrobots,” exhibit this behavior, too. “The organism as a whole no longer responds as it had, but subsets of cells are active, decision-making, and problem-solving,” Miller says.