Mold is part of our natural environment. Mold works in nature by breaking down dead organic matter such as fallen leaves and dead trees. Without mold, we would be up to our ears in dead plant and animal matter! While mold is natural and normal outside, the growth of mold indoors should be avoided. Mold grows in the indoor environment because mold spores, which are already present indoors colonize or grow in a given area where there is a good food source and sufficient moisture. A recent study discovered that mold often flourishes in places you'd least expect. Mold is found on 88% of windowsills, on 83% of refrigerator seals, under 82% of sinks, and on 49% of shower grout.