Question mark
The rhetorical question mark or percontation point was invented by Henry Denham in the 1580s and was used at the end of a rhetorical question; however, its use died out in the 17th century. It was later revived in modern-day society by Matt DiRoberto. It was the reverse of an ordinary question mark, so that instead of the main opening pointing back into the sentence, it opened away from it. This character can be represented using the reversed question mark (⸮) found in Unicode as U+2E2E. The percontation point is analogous to the irony mark, but those are even more rarely seen.
Button (poker)
The use of other small disks as such markers led to the alternative term "button". Silver dollars were later used as markers and it has been suggested that this is the origin of "buck" as a slang term for "dollar," though by no means is there universal agreement on this subject. The marker is also referred to as "the hat". The origin of this term is believed to stem from the wearing of a hat having been used to denote dealership.