​What is this little box with a chevron pattern on my kitchen wall above the pantry in my 1950s-ish apartment building?

I live in an older apartment building and this little box/wall attachment has been heavily painted over above the pantry? I’ve lived here 5 years and I suddenly cannot rest until I know lol. It’s about two inches tall. There is nothing behind it on the other side of the wall. I removed a bit of the paint with acetone and it seems to be metal? sounds kind of hollow? I might just have to buy some paint stripper and uncover all of it if I can’t figure it out! Thanks a bunch!