Pick up a button mushroom from the supermarket and it squishes easily between your fingers. Snap a woody bracket mushroom off a tree trunk and you’ll struggle to break it. Both extremes grow from the same microscopic building blocks: hyphae – hair-thin tubes made mostly of the natural polymer chitin, a tough compound also found in crab shells.

As those tubes branch and weave, they form a lightweight but surprisingly strong network called mycelium. Engineers are beginning to investigate this network for use in eco-friendly materials.