I have two, what did they use to be?

Idk, but apparently you got minerals for them.

I've 2 and payed 48 each.

DLDB advertisement item is/was that I guess...

Ah, that sounds right.

Why were they removed?

I still have one

Right click, view image location or the like. should give you some hint as to what it is.

Right now, there's no way to check if you've already bought and activated an item if you've already used it (except to physically look for the effects of its usage). Just a tad unintuitive. And by "unintuitive", I mean "very, very irritating". :\

I haven't used it. I bought them because they were -10 and -2 minerals or something.

I have two too. I think it's an avatar expansion or a PM expansion or something.

I also found two excalibans. Used one. I'm guessing those were trophies of moose appreciation...