Drill and a mystery item

[Wallhangers]

Last evening I hunted a field that has given up tons of great artifacts over the years but gets pounded by many. I spotted this broken drill first and then I found this interesting piece. I thought it was just a piece of plastic or fiberglass when I first picked it up, but after further review, it appears to be bone. It is really thin and polished and has the two straight lines running across. It reminds me of bone you might find from a shoulder blade on a small animal. Any ideas on this one? Thanks,