cells

We have about 100 trillion cells in our bodies, made of molecules, mostly empty space, except for atoms, mostly empty space. These cells are being replaced constantly. Some regenerate every day or so, some last much longer. It's safe to say we don't have any body parts that were there a few years ago.

Trees do the same thing with their cells. Some shed their leaves all at once, some gradually, while the rest of the tree replaces its cells slowly but constantly, as we do. Flowers disappear, leaves and all, and return in the spring.

What if we shed our cells all at once? Would we disappear, or just be invisible? Notice these are not the same, because by disappearing I mean left town, maybe for a day, maybe for the season.
This is something I think about when I get a haircut or trim my nails. Try not to think about it in the middle of the night.