Mother nature is a real softy: many of her structures won't stand up to the gentlest breeze. So why isn't she collapsing around our ears?
Look at a hinge on the nearest door. Its halves slide smoothly around each other and around their centering pin. Then look at the ears of a cat or dog as it turns to face some rustle or squeak. Muscles pull on cartilage, twisting each structure around its pivot, and skin stretches to accommodate the motion. These ears are hinges, too, but they’re made from flexible materials that bend instead of solid parts that slide.
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Better Bent Than Broken