Dream About Black Mold In Old Room

I had a dream that I walked into my old room. It was white and empty except on of of the walls and part of the floor that was a bunch of black mold growing. My twin sister was in the room. She was shoveling out the black mold. I asked her what she was doing and that she shouldn’t be in there because there was mold. She continued shoveling and said to me. Yes but it’s doing exactly what mold should be doing.