Black mold on cement board.mold; rust; black; streak; page; cement; dirty; brick; floor; stone; aged; fissure; stains; rock; crack; break; peel off; fracture; burst; abandon; old; gray; building; concrete; abstract; historic; ragged; wall; decay; backdrop; texture; fungus; architecture; plant; damaged; thallophytic; clay; grime; plaster; art; antique; vintage;