Single mattress - not perfect (Poole, BH15)

Single sprung mattress. Dimensions in photos length, width and depth. It was my spare for about 5 years, used with mattress protectors. Have been intending to post it here for a couple of weeks. Unfortunately I have just noticed a tiny piece of metal poking out of one side. I think it might be the end of a spring as it seems to be attached to the frame. Before I take it apart to dump does anyone have a use for it?