Michael Black wrote:

And oddly, you can have mold growing on items that do involve mold. I
better throw out that yogurt, because while the process of making yogurt
involves mold, that bit sitting at the back of the refrigerator for too
many weeks has some other unwanted kind of mold on it.

Michael

All true... I was taking some liberties, saying cheese == mold.
The point was that for most (aged) cheeses, the primary mold to grown on
it is the same as grew in it.
As for yogurt - you're right to toss it. Yogurt is fermented by a
bacterium, and any mold you see is a foreign overgrowth.

Dave