Have you ever heard of flesh eating fungus?

In fact, we are all constantly being attacked by fungi. We breath their spores and they start to grow like they would on your piece of damp bread in our windpipe and lungs. They also try to grow on our damp lips, armpits, groins, genitalia, etc. Fortunately for most of us, our immune system is quite good at killing and eating up the fungal growth, that is, until we suffer a collapse of our immune system, or we encounter a particular nasty type of fungus. Then, it is dust to dust.