Can anybody tell me what this is or what it’s for? I’d say they are from the 40’s or 50’s and made of glass. We have a set of 12. We found them in my father-in-law’s kitchen after his passing. They are about 5 in across and 3 1/2 in deep. It has 3 places where it pokes out of the bottom(?) like nipples which you can see best in the 2nd pic.