Imagine taking a spare shoelace, one end in each hand, and holding it out in front of you so that the shoelace is nice and tight. What happens when you bring your hands closer together? The shoelace sags, forming a U-shape. Now return your hands to the original position. What happens if you pulled harder? You’d break the shoelace.
Researchers in both France and the UK have found that silk fibers from orb spiders don’t act like your shoelace in either of those scenarios! When you compress the silk, it stays tight by transforming some of the fiber into liquid droplets and avoids sagging. When you extend it, it also stays tight without snapping because of the molecular structure. They also developed a synthetic system that mimics silk in this way. This is explained in their recent paper and in the movie below.