A surface covering unit includes at least one face comprised of at least one primary rotational tessellation element. The rotational tessellation element includes at least two pairs of sides, and the sides in each pair of sides have the same length and are images of one another. The sides of a first pair of sides extend from a first vertex and are rotationally spaced from each other, and the sides of a second pair of sides extend from a second vertex and are rotationally spaced from each other. The sides of the first and second pairs of sides have two or more straight line segments or complex curves, and are not a single straight line or a single curve. One pair of sides has a length different from the other pair of sides. The surface covering has a natural appearance such that a repeating pattern is not readily apparent.