Repeating a shape, left to right and up to down is the simplest of symmetry systems. A translation in techno talk. Square tiles on the floor is the best example. Here I’ve drawn an eye in West Coast Formline style. The repeating directions are skewed to 45 degrees in this case.
Ovoid Eyes tessellation by Francine Champagne, ©2015
And here is the zoomed-out drawing.
Ovoid Eyes tessellation by Francine Champagne, ©2015