Xenobots gather loose cells into new copies of themselves
Some xenobot shapes sweep loose frog stem cells into piles that mature into new motile constructs, a form of replication the authors call kinematic self-replication.
What happened
Spherical clusters of frog embryonic cells, placed among loose dissociated cells, moved around and pushed those cells into piles. Some piles matured into new motile clusters that could repeat the process. Replication normally died out after one or two generations. A shape designed by computer, a C-shape resembling the arcade character Pac-Man, sustained more rounds of replication.
Why it matters
This is a kind of reproduction that is not growth or budding: the parent assembles offspring from material in its surroundings. It shows that collections of cells can have reproductive behaviours that their source organism never uses.
Caveats
Replication depends on a carefully prepared supply of loose cells in a dish and stops when that supply runs out. The constructs cannot evolve or persist outside lab conditions.