Skin Memory

I manage to inject a freshly sharpened pencil into the sole of my foot while moving a chair. After firmly pressing an alcohol-soaked cotton ball over the wound for a couple minutes, I realize that the graphite of the "lead" will probably be visible for at least twenty years. For the first time in a decade, I locate a faint grey dot to the left of the first knuckle on my third finger, the result of defensive pencil-play that dates back to grade school. I'm assuming this version of scarring works on the same premise that retains tattoos over the years, but why? How's it work? I know that every seven years, as new skin is formed, the bottom-most layer of skin is forced up to the barrier that separates the inside of the body from the outside (this rate of travel is what I call "the speed of dark"). It is then released into the atmosphere where it combines with boogers and star-matter and, inevitably, turns into dust. So what are these marks? Residual ink and graphite that stays around longer than the skin? Doesn't that grow out too? Has the memory of some implanted color been etched into the reproductive intelligence of my skin's cells? Is my skin re-living some past trauma or is it learning? I wonder what else it knows.