Any ideas what this might be, before I hack at it? A thin skim of plaster fell off as I was taking off the wallpaper. It's iron or steel, about an inch wide with a bevelled edge, and runs from the ceiling as far as the round magnet I've left stuck to it in the photo. I've run the magnet over the rest of the wall and that's all there is. It's not beading- as well as not being full height it's several inches from the corner and is solid (or at least angle iron).
https://imgur.com/a/hLN2g3V
Any thoughts gratefully received.
https://imgur.com/a/hLN2g3V
Any thoughts gratefully received.