Old radios too [1]. A few years back there was an intense discussion on some antiquarian site about what the function was for a central hole in an otherwise beautiful antique wooden philco radio cabinet. Finally some bright old duffer shows up and allows: "Oh, that's where the 'magic eye' went". Of course, the rest thought he was just pulling their legs about there being a "magic eye" on these things.
[1] https://mikesradiosandstuff.weebly.com/uploads/1/0/8/7/10875...