We, humans, have swirly stripes imprinted on our skin. We can’t see them unless we’re not infected with some particular skin diseases. They’re called Blaschko’s lines and they can appear anywhere on our body.
These lines are invisible unless you’re suffering from a skin rash (like lichen, for example), Chimerism, X-linked genetic skin disorders, or other pigment-related disorders. The stripes follow wavy shapes on the head, “S” shapes on the chest and the sides, and a “V” shape on the back. They are believed to be the traces of our embryonic cells’ migration. Alfred Blaschko, a German dermatologist, first raised awareness to these stripes back in 1901, thus, they are named after him. The lines aren’t linked to the muscular, nervous or lymphatic systems in our bodies and they don’t correspond to them. They are a type of a genetic mosaicism and can be observed on people even as young as 3 year old infants.
Not only that, but they have been known to appear even on domesticated animals, such as dogs and cats.