From the WSJ - Mystery Molds
Q. I’ve been told not to eat food that has a little mold on it because the mold has permeated throughout. Is this true?
A. Yes, mold that is visible on the surface of food is only the tip of the iceberg, according to the United States Department of Agriculture.
Molds are fungi that have three parts: the root threads, which invade deeply into the food; a stalk, which rises above the food; and spores that form at the end of the stalk.
By the time the stalks are visible, the root threads, called hyphae, are embedded, so it is best to avoid food with any sign of mold.
I am severely grossed out right now, my mind is racing back to all those times I cut a bad corner off a slice of bread or a block of cheese. Ewwwww.