There is a test one does on old spools of thread to see if they are still viable for sewing. Unwrap a few inches and give it a sharp yank; if it snaps off, it's too brittle. I had a lovely box full of thread from my mother's house and it added up to 96 spools, many of them wooden (none so old as stone, she wasn't born in the dark ages).

Did you know that you can sell this now-worthless thread to people on eBay? Maybe they buy it for the spools (but quite a few of mine are also plastic). I looked around and have a price in mind and some lovely photos of these defunct tubes of cotton. If I learn later that is there some fabulous craft idea that brings in megabuck$ for items made with these old spools, I'll take my troubles down to the Legion Hovel and we can discuss where to find more old useless spools of thread.