Whatever it is, my guess is that it should be rotated as shown below, with the symbol being that of "infinity" .. I would venture a guess that it is indeed a buckle, but we really do need to see the back.
I've seen the symbol before but I can't recall it, it looks like it is colse to 8" at the widest point. I'm judging that using the high powered bullet holes in what looks a gong plate that it is displayed on.
I assume that information is from this listing?: Vintage Bicycle Racing Porcelain Number 8 Sign Rat Rod Antique Emblem Bike NR
They don't seem quite positive, which doesn't mean it's incorrect, but I somewhat feel another source would help confirm it. Their pictures of the back give some added detail that does help.