What Is It? Working on Project and got some interesting stuff to look at..

I was working on a repair and of course I wanted to be able to take photos and video. In the process I took some interesting shots (or at least I thought so). Let me share them and see if you know what they may be.'

Here is a small spot/stain that was removed, what do you think it is? Should be fairly simple, I think.
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View attachment 25803

here it is removed
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Here is one that was interesting to me....

What Is It? Working on Project and got some interesting stuff to look at..