Me too, bottles in campfires, melted window panes from house fires, etc... I've metal detected several old home sites where the home burned and found deformed marbles. Many of thos old homes were made of heart pine (longleaf pine) which was full of pine tar pitch and burned very hot.
I have the remains of a Pressman Big Shot box of Alleys that was in a fire and all that is left is the melted glob of marbles.
Very cool piece hdesousa. The ridges underneath look like quarter sawn wood grain. Here's mine, not nearly as old but same concept.