You open your lunch box and you pull out a freshly packed sandwich. You’re hungry, your stomach is rumbling and you can’t wait to munch it down. As you are inches away from biting down you notice a strange fluffy blue layer. Your jaw comes to a halt after you realize that the bread is moldy. Is it safe to just rip off and continue eating?
Well, when mold first comes into contact with the bread it anchors it’s “feet” down into the nutrient rich environment. As it absorbs more nutrients the mold grows more inwards, elongating & intertwining it’s foot hold. Almost like the roots of tree.
Some molds such as Rhizopus stolonifer grows primarily as mycelia and forms what we call a mycelium mat. In case you were wondering what that was it looks something like this.
Once the mold has a solid anchor and the conditions are right, reproduction begins. That is, the mold begins to produce an upright stalk (known as sporangiophores) with an enclosed sac (the bread mold we see). Budding occurs shortly after.
So what does that mean? Well, when you rip off that little piece of mold it may have already penetrated the whole entire slice of bread. Similar to an ice berg, the top is only a very small fraction of what is really happening underneath.
When in doubt, just toss.