Series 2009A. $100 Bill Unusual Star, What Is This?

This is not a star. Why do you think it is ususual? Please be specific.



to the CCF!

It also has some writing and another stamp on the top corner. As it is it's a face value note and nothing more.

Yep, the little black star is a moneychanger's stamp, or "chopmark", applied by moneychangers (mostly in Asia) to indicate that a note they have handled is in their opinion authentic. Not applied when the note was printed and therefore not an error.

It only looks like it's "underneath" the other printing because the water-soluble ink on these stamps the moneychangers use does not stick to the glossy, sparkly banknote ink, only the relatively clear paper, so the stamp only appears in places where that ink isn't. But it is, nevertheless, a moneychanger's stamp and not something applied when the note was printed. 100% guarantee it.

You can go down to Office Depot, buy yourself one of those little self-inking stamps, and make your own chopmarked notes. They would look pretty much the same as this. I wouldn't actually recommend doing this though, since deliberately defacing a Federal Reserve note is borderline illegal in the US (but it's not illegal overseas, which is why the foreign moneychangers have no problem doing it).

They call that "Microprinting". It's one of the many security features.