Researchers at Durham University and the Fraunhofer Institute developed what they say is the first manufactured non-cuttable material.

The engineers were inspired by the tough cellular skin of the grapefruit and the fracture-resistant shells of the abalone sea creature.

The lightweight material is made from alumina ceramic spheres encased in aluminium foam. It works by turning back the force of a cutting tool on itself. The material could not be cut by angle grinders, drills or high-pressure water jets. When cut with an angle grinder or a drill, the tool becomes blunt thanks to the ceramic spheres. In addition, the ceramics fragment into fine particles, which fill the cellular structure of the material and harden as the speed of the cutting tool is increased.

“Essentially cutting the material is like cutting through a jelly filled with nuggets,” the researchers say, “if you get through the jelly you hit the nuggets and the material vibrates in such a way that it destroys the cutting disc or drill bit.”

Water jets are also ineffective because the curved surfaces of the ceramic spheres widen the jet to substantially reduces its speed and weaken its cutting capacity.

Called Proteus after the shape-changing mythical god, the material could be used in security, health and safety industries to make things like bike locks, lightweight armour and protective equipment.

Images: Fraunhofer Institute / Durham University (via New Atlas)