['Arguably gross, but probably of interest.' Having spent several years brushing bits of scab off everything in her immediate environment (clothes, furniture, flatmates) Sam's absolutely inured to the 'arguably gross' aspect.]

I should probably cover scabbing so you have some kind of context. It's part of the process of an injury healing, provided the injury is something like a cut or a scrape. The brutally abridged version? The blood flow at a wound site triggers a chain of events for forming a kinda combination shield-and-plug to close up the injury as quickly as possible. The faster it's closed, the better, because that means blood loss is minimized, and there's less of a window for germs to enter the body since that's kind of a big thing with organics---infections are a talk of their own, I tell you. But! Just being closed, a scabbed-over wound isn't healed; the scab stays where it formed to protect the wound as it does heal, since the tissue forming for it will take some time. Once it's far enough along, the scab dries out and eventually falls off.

Scabs can be picked off, too, but it sometimes hurts to do that, and if you try too soon you might just reopen the partway healed wound. You're also likely to get a scar if you pick a scab---or so I was always warned.