I see what you mean, but not a suction cup.It does look like a suction cup though.
Not a vacuum tip.A precision vacuum tip? Like for keyboards and stuff?
Yes: a LensPen tip. I delibertately showed it much larger than reality in order to make it hard to guess... Over to you!Lens cleaning tip
I tend to agree. Often this turns out to be more like "Twenty Questions" where the image is almost irrelevant.OK, I see your point.
For me it starts however from the image. If there is not a clue, even a distant one, me (weak-minded) won't start guessing.
Leaving Q&A for others.