Transmission Question - How concerned should I be?

[CleaningTheGarage]

First time changing the fluids today and found this in the dimple in the bottom of the transmission plug. (See pics).

The large piece appears to be part of a gear tooth. I'm obviously concerned about it, but don't know to what extent I should be. Where on the spectrum between "Don't move it, don't let the gears turn or engage until the whole thing is broken down and rebuilt" on one end and "Ah, that's normal for an A. Keep driving until it sounds like popcorn and won't stay in gear" on the other.

Any help on the scope of the severity, causes, options for remediation and preventive measures would be greatly appreciated.

I have a lot I want to get done in a short time to get her road worthy and I'm trying to prioritize the order in which I fall down rabbit holes.

Thanks!