ᐅ "Black spots" – could that be mold?

Hello,
today, while removing the wallpaper, we made a discovery: around some windows on the upper floor, there are black "spots." When you touch them with your finger, the black substance stays on the finger. At first, we thought they might be insects, but these things don’t move.

Can someone tell me what this might be?
A photo is attached.

Thanks,
Regards, Patrick

Yes, mold

ok, thanks a lot

I think that looks more like something from a plant... it looks very regular, or are we not talking about those sticks?

Have you ever measured the moisture levels in the affected walls?

Please take a close-up shot.