a window into the flesh?

yes there's flesh under there

if you press on the nail you will blanch that flesh

it will blanch, as you press the the blood away

if that blood is not well oxygenated it will darken toward blue

if you bleed neith the nail the blood will tend to stay there
cause there's just nail on that side
and if there's a lot
the nail will tend so seperate

A window? Yes, but so is the skin.