I have an old dumpsite on this ranch I live on and have found tons of bottles. I always find these clear marble like balls scattered about. Each time I come accross a bunch of bottles, the marble looking things are always amongst them. Are they part of the lids? I read that some of the older types of bottles had glass marbles in the tops, I guess like stoppers maybe, and that kids use to break the lids to get to the glass marbles. does anyone have any info about this?