Face button, maybe bone?

I found this in my grandmothers sewing notions, and have no idea if it's old or new, or material. I suspect it's bone, as it doesn't feel or sound like plastic, but I'd appreciate any information about it.

I didn't have a ruler, so pictured it on a large (not laptop sized) sized keyboard, to try to give some idea as to size.

It's kind of cute and I may use it on one of my crochet projects, but only if it's fairly worthless so I won't have to worry about ruining it.