Shapes of [biological] cells

Many types of cells are arranged like typical 3D packings of deformable objects (see page 988)—with considerable apparent randomness in individual shapes and positions, but definite overall statistical properties. Cells arranged on a surface—as in the retina or in skin—or that are intrinsically elongated—as in muscle—tend again to be arranged like typical packings, but now in 2D, where a regular hexagonal grid is formed.