When a deer, cockroach or elephant dies there are a whole string of events that take place to insure that (a) said animal is not lying around stinking up the countryside, and worse, (b) spreading germs around that will create biological havoc.
The process of cleaning up and recycling dead things in the wild usually begins with the scavengers. During the summer around these parts, that's the handsome turkey vulture, the clever coyote and a whole lot of other opportunists. Once vultures, coyotes, woodpeckers, hawks, eagles, owls, weasels, skunks, mice, rats, squirrels and other so-called "higher " organisms have gleaned all they can, insects take over.
Fungi are everywhere and there's nothing you can do about it, except move into a glass jar; but even then, I'll bet some of the tiny, tiny spores fungus are famous for will get to you.
That said, here comes the science lesson:
Fungi are plant-like organisms that are one of the "Five Kingdoms of Life;" they lack chlorophyll and do not require light to live. (Please forgive me if you already know, but chlorophyll is the green stuff in plants.) Many fungi are useful in the human perspective (edible mushrooms for one), but some cause problems manifested as sickness and injury to plants and people.
To digress, The "Five Kingdoms of Life" are, not necessarily in order of importance, but as to biological complexity, as follows:
Monera: This Kingdom includes single-celled organisms that do NOT possess a nucleus. Examples are bacteria common in soil, NOT dirt. They play an important role in decomposition of organic materials, a vital piece of carbon cycle. Another example is blue-green algae.
Protoctista: This kingdom includes the simplest single-celled organisms that DO possess a nucleus. Examples include nucleated algae and slime moulds.
Fungi: These eukaryotes lack flagella and develop from spores. ("Eukaryotes" are cells organized into complex structures enclosed within membranes.) Examples include yeast, moulds, and mushrooms. WARNING! DO NOT eat wild mushrooms unless you are POSITIVE they are edible. Eating the wrong amanita mushrooms can ruin any plans you may have for the future. Although there are some edible mushrooms in this genus, in my book, NO amanita should be eaten!
Plantae: These eukaryotes develop from embryos and use chlorophyll. Examples include mosses and vascular plants, such as trees and sagebrush.
Animalia: Eukaryotes that have cells that are multi-cellular and develop from a blastula (a hollow ball of cells). Examples include worms, arthropods, animals and you and me.
Since fungi do not have chlorophyll, they absorb food from other sources, and since they don't use (need) light to make food, fungi often live in damp and dark places. The first problem occurs with fungi that are supposed to "eat" things when they are dead, but sometimes they go off half-cocked and start eating when the organism is still alive. That's when a mycologist gets into the picture to help figure out what to give to the infected patient or plant to get rid of the fungus.
Most fungus can also make some big things happen in food, such as yeast in bread. The same yeast, Saccharomyces cereviseae, is used to make alcohol in beer.
Moreover, here's a big one in favor of fungusamongus: without powerful fungi, we would have piles of trash everywhere, because fungi obtain food from our trash, and make it into soil. I say again, not DIRT, but SOIL. ("Dirt" is "soil" we have ruined.) The next time you go past Knott Landfill, pay attention to that lovely aroma, that's fungi at work making soil.
Some fungus gets a bad rap because it's trying to do its job way too early to an organism. In humans, it's called ringworm, but there is no worm involved, it's just the way that fungus likes to grow, and be warned - you can catch it from other people.
Ringworm is the kind of fungus that gets on the body, but some fungi gets inside and causes allergies. Over 37 million people have allergies and a fungus causes many of them. Buildings can also get sick because of too much fungi, such as Penicillium and Stachybotrys that float in the air and cause watery eyes, sneezing and breathing problems.
We also have smut fungi that grows on grains, such as wheat. "Smut" refers to the ripe galls filled with dark sooty spores that form when the fungus infests a plant.
So now you know what fungi is, why it is necessary to have around for us to live a healthy and productive life; enjoy our meals more fully with delicious "store-bought" mushrooms, and why we have and need healthy soils. One of the unequivocal "Laws of Nature" flatly states that if we do not take good care of our soil we will all die. Fungi helps us to stay alive.