I found this heavy round steel plate buried in a kitchen drawer with other accessories for a vintagey JennAir range after we bought our house years ago, and never got rid of it because I thought maybe it was important. I can't figure out what it's for, where it goes, or even IF it's for the range. It's about 8" in diameter, very heavy gauge, smooth (except for some slight corrosion/rust bubbles) on both sides, and one side has three little welded-on clips. It's too big to use as a blocking cover for the convection port inside the oven, and the clips don't seem to let it fit over the burners as some sort of "simmering" diffuser (it's an electric range... pic also attached). Any ideas what it is?