Water is the key. Without it, molds can't get started, much less spread. But when water is left to sit for even 24 hours, common molds can take hold.
Molds are simple, microscopic organisms, found virtually everywhere, indoors and outdoors.
Molds can be found on plants, foods, dry leaves, and other organic material. Molds are needed for breaking down dead material. Mold spores are very tiny and lightweight, and this allows them to travel through the air. Mold growths can often be seen in the form of discoloration, ranging from white to orange and from green to brown and black. When molds are present in large quantities, they can cause allergic symptoms similar to those caused by plant pollen.