Hello, we just noticed this strange white fungus growing on our door today. It wasn't there last week. It has been a little wet the past few days here but the door has seemed dry. This is an interior surface of a wood door, there is no other mold/fungus anywhere else on the doors. Any idea what may have caused this? There are little black spores in it. What is the best way to remove it? Do I need to worry about these spores spreading in the house?