Scrap metal on the floor. It’s like someone just left a bunch of their junk there. This is, of course, what recycling plants are for. Instead, junk is left on the floor of a museum for someone to trip over. The museum should get one of those electromagnets you can find in a scrap yard to get rid of this piece.
It looks like there is salt on the floor, mixing with water. It creates a corrosive effect on the steel. Coal is used to make steel.
The thing about the McElheny’s piece is that it’s one of those crazy new age contraptions. Crystals and stuff like that. This must have to do with pyramid power from the 70’s. It’s supposed to keep milk from going stale, razor blades from going dull, and possibly apples from going bad too. Saw it on Mythbusters one time. They proved that pyramid power wasn’t all it was cracked up to be. Must have just been a fad.
Fads come and go.