Here's the shaggy mane mushroom, or
Coprinus comatus. It moved in on our bucket early on, before many other decomposers had reached it. The shaggy manes mushrooms are growing out of the brown paper we had used to cover the top of the pile to absorb moisture. The black stuff behind them is actually spores that they have released over the pile. The older mushrooms that have already released spores are wet and inky looking. This is their method of dispersal, where the cap dissolves and the spores are released into the air. Some are so spent that they are just inky stems barely peeking out of the ground. Coprinus mushrooms start out looking velvety, hence the name, with a layer of delicate white fibers covering the cap and stalk. Their velvety fuzz becomes a mane of shag. Over time, these mushrooms grow again from the spores and the cycle of breaking down the organic matter below and creating rich soil continues.
There is something incredible about soil. It is full of space! A single tablespoon of clay is like a small galaxy of flat crystals stacked on top of each other, full of surfaces for stuff to attach to. For an ionic molecule, there is enough surface area in that tablespoon of clay to cover a football field! There's all sorts of things attached to the insides of clay bits. The same goes for the leaf litter and soil in the backyard. It's a whole world contained within the universe of a few square inches. There's spiders, red wigglers, millipedes, moles, grubs, beetles, ants, mice and tons and tons of fungi. All these guys live inside all the crevices and nooks in the litter layer that they make their home. Below the leaf litter, if you dig around under there, you'll find the layer of organic matter, the humus (hyoo-miss). Humus comes from all the pooping going on. The humus appears because the leaf litter is eaten down after time, by smaller and smaller things all the time that eat the leaf bits into smaller and smaller pieces. After a while, the bits are so small that you get a rich, black humus that smells like excellent food. It's so protein-rich, in fact, that a person could survive on it if they got lost in the woods.
Ever tried composting kitchen scraps? If so, you might have read that you wouldn't just throw your scraps in the yard and hope that it breaks down. You have to mix your nitrogen-rich scraps with some source of fiber high in carbon, such as dry leaves, yard waste, newspaper, sawdust, napkins, ash,
etc. The nitrogenous waste has a very strong smell. Once you mix the two together, stuff breaks down easily and you get a pleasant, mild compost-y smell. Poo is also high in nitrogen and organic matter, just like kitchen scraps.
That's what it all comes down to, eating and pooping. Detritivores eat the detritus, the decomposing organic matter, and turn it into soil. It's no coincidence that our poop and soil (detritivore poop) are often so similar in color. Both are things that used to be bigger and now are made up of very small bits stuck together. Both are things that are darker in color the more organic matter is present. Both have a rich smell: the more pungent the aroma, the more organic matter that has not yet been broken down. Poop and soil are made for each other.