Taking inspiration from the toughness of the marri nut, which is a hard seed of the marri tree native to Western Australia that is so strong even its natural predators have trouble breaking it, a team of researchers at NYU Abu Dhabi, have developed a natural design that could potentially pave the way for new materials used for protective gear.

To do this, the team studied how the nut absorbs impact and resists cracking, discovering that the marri nut's strength comes from a layered internal structure that blends a tough outer shell with a softer, flexible interior. This construction enables the nut to absorb energy without shattering, thus distributing force in a controlled way instead of breaking suddenly.

Source: Recorded by D. Blumer and reproduced with permission of the Botanic Gardens and Parks Authority

"What makes the marri nut remarkable is how it balances strength and flexibility within a single structure," the researchers explained.

To make this determination, the team used advanced 3D imaging and mechanical testing to examine how the nut behaves under pressure. Although made largely of cellulose, which is a natural plant material, the nut possesses a rare combination of properties: It can deform and absorb energy while simultaneously maintaining stiffness and remaining lightweight.

Taking inspiration from this design, the team created a bioinspired material that replicates the nut’s internal structure.

An article detailing the material, “On the Origins of Toughness in Corymbia calophylla (Marri Tree) Nuts,” appears in the journal Advanced Science.