Why your nails never stop growing

Your fingernails are essentially hardened shields of dead protein pushed out by a factory hidden beneath your cuticles. This factory, known as the matrix, never takes a day off. It produces new cells so aggressively that the older, hardened ones are forced forward at a rate of roughly 3.5 millimeters every month.

Fingernails on your dominant hand actually grow faster than those on your non-dominant hand. Constant use increases blood flow to the fingertips, delivering a surplus of nutrients to the matrix that fuels a quicker production line. If you are right-handed, your right middle fingernail is likely the fastest-growing part of your hands.

Toenails operate on a much slower timeline, growing at about a third of the speed of fingernails. This discrepancy likely stems from the fact that toes receive less circulation and are often cramped inside shoes, which limits the oxygen and blood flow reaching the matrix.

Every nail you see is composed of keratin, the same durable material that makes up a rhino's horn or a bird's beak. These cells are technically dead by the time they emerge from the skin, which is why you can clip them without feeling pain. They are the translucent tombstones of cells that were alive only days prior.

Despite the popular myth that hair and nails continue to grow after someone dies, the process stops the moment the heart does. The illusion of post-mortem growth occurs because the skin dehydrates and shrinks, pulling back from the nail beds and making the existing nails appear longer and more prominent.

If you were to lose a fingernail entirely, your body would need up to six months to replace the shield from scratch. A toenail can take a full year to complete the same journey from the root to the tip of your toe.