George de Mestral pulled a burr from his trousers and put it under a microscope. His dog had picked them up too. Under magnification, the stubborn little nuisance revealed a system of hooks.

The two of them had come home from a hike through a patch of brush, covered in the things. Most of us know what to do with burrs. You pick them off and grumble at the dog the whole time. De Mestral, an engineer by training, carried one to his microscope.

The lens showed tiny hooks all over the burr, each one caught in the loops of his trouser fabric or tangled in the dog’s fur. That grip is how the plant spreads its seeds, riding along on whatever brushes past. He wondered whether people could fasten things the same way, with hooks on one side and loops on the other.