Human skin is completely covered in invisible, alternating stripes and swirling patterns known as Blaschko's lines, which follow the paths of our embryonic cell migration.

A closer look

Human skin is completely covered in invisible, alternating stripes and swirling patterns known as Blaschko's lines, which follow the paths of our embryonic cell migration. These patterns are completely invisible under normal lighting conditions, but they can dramatically appear as literal tiger stripes or massive spirals if a person develops certain genetic skin conditions or chimerism. The cells essentially map out the exact journey they took when you were just a microscopic cluster of tissue furiously trying to organize yourself into a functional human being. So beneath your boring, uniformly colored exterior, you secretly possess an elaborate set of invisible zebra stripes, proving that human biology is infinitely weirder and much more visually interesting than anything we can actually see in the mirror