Self-assembly is ubiquitous in the natural world, serving as a route to form organized structures in every living organism. This phenomenon can be seen, for instance, when two strands of DNA—without any external prodding or guidance—join to form a double helix, or when large numbers of molecules combine to create membranes or other vital cellular structures. Everything goes to its rightful place without an unseen builder having to put all the pieces together, one at a time.
source https://phys.org/news/2021-01-molecular-nanofibers-stronger-steel.html