Black mold has a spotty appearance and is usually greenish-black in color. Mold and mildew can be found anywhere there is a lot of wood, e.g., living areas in homes, drywall on walls and ceilings, floorboards, roofing felt paper, lumber used for construction or furniture making. Basically, if there are any areas where the moisture from the water gets trapped and starts to rot the organic material, it will often start to grow black mold over time. See the list of some of the best cleaners for mold in the shower.