What are the types of scabs that's nearly impossible to pick off, it's as if it's embedded into your skin?

Don'tLabYourScabs: That's the kind of scab telling you to lay-off, that it's not ready yet to come off, that there's still some healing to do inside and if you pick at it, it will just take longer to heal or worse, get infected. Only very rarely does a scab just infinitely sit there- and if it does, a doctor should take a look. Maybe there's a piece of something in there, or a smoldering something underneath.