On a curved hill, people at the top spread out: there’s more elbow room, while down in the hollow they crowd together. The same principle works in living tissues: on convex regions, cells grow larger. Robert Hooke saw cells back in the 17th century, never suspecting their size was dictated by the geometry of Euler and Riemann. A computer model of an egg-shaped surface confirmed it: curvature changes the perimeter-to-area ratio, contact tension drops, and the cell expands until forces balance. No chemistry needed, just the mechanics of shape. The number of corners doesn't matter: a five-sided cell behaves just like a six-sided one. This geometric law is universal: it’s what makes water flow under gravity, disorder increase, and spacetime curvature bend light around galaxies, where dark matter crushes stars to the density of a neutron star, and even the Big Bang obeys it. Perhaps from the landscape’s shape we’ll spot signatures of life made of carbon on distant planets.