Re: Has bread mold already 'eaten' through the bread by the time it is visible?

You are both right.  As mold grows it sends out hyphae similar to roots of 
a plant.  As with a tree, we see the structure above the ground but below 
the ground are roots extending outward.  With mold it is much the same.  
On a piece of bread, there might be a visible portion, but below the 
surface the hyphae could extend well beyond the fuzzy colony on top.  The 
mold organism needs oxygen to grow so the hyphae usually do not extend too 
deeply into the food.