But what we don't know is why they become susceptible to this host of pathogens, viruses and fungus.

And this town has a very, very high potency of fungus.

These are not single individual plants; each one is a symbiotic combination of an alga and a fungus.

But this particular fungus nibbles away only at certain layers in the wood, leaving other layers alone.

He basically exposed the wood to a species of fungus, uh, a mushroom.

But to me, what's most interesting about this process is how it may enable fungi to help clean up environmental pollution in the soil.

So the fungus can absorb this material and get nutrition.

A fungus secretes enzymes into the soil, enzymes that break down, decompose organic material in the soil.

And fungi in general are often an important active component of the soil.

But a fungus like that...most of it actually lives underground. 

When you try to imagine a fungus, you'd probably picture a mushroom popping up out of the ground.

And although regarded as microorganisms, filaments from a single fungus can fan out to occupy many square meters or even several square kilometers of forest floor.

Filamentous fungi grow in soil and in decaying vegetation.

And the chitin in the cell walls of a filamentous fungus...a filament, of course, is a long thread-like structure, cells joined end to end.

For example, in highly acidic soils where few bacteria can survive, fungi frequently become the chief decomposers of organic matter.

So then we had several kingdoms for plants and for animals, and the different kinds of fungus like mushrooms, and for these tiny bacteria.

So in this case, the splitters eventually won, and got a third kingdom just for the fungus.

Take for example the mushroom, a fungus.