^^^ possibly some spores the mushrooms dropped during harvest/processing.
My pasta sauce starts with a slow sweat of even 1/4" diced yellow onion, paper-thin garlic slices, fennel seed, black pepper, salt, 1 bay leaf, crushed red pepper, dried thyme, dried oregano, and a good amount of EVOO. Once sweated and the onions are mostly not crunchy anymore, I add in some cans of Escalon 6-in-1 crushed (the best) or Classico crushed tomatoes. I let it simmer for 25 minutes with the lid off, stirring every 5-10 minutes. I don't prefer to cook it more than 25 minutes but it's really only done when the onion in the sauce is just the right texture; not mushy but absolutely no crunch, which is why an even 1/4" dice is crucial to start. When there's about 5 minutes left I add in hand-torn fresh basil and let it finish simmering. Once done simmering I pull it from the stove, remove the bay leaf, and put the stick blender to it until it's the right texture, finally stirring in a basil chiffonade at the very end for aesthetics and a little extra flavor.
The end result is what I consider perfect. When you're done eating your bowl of pasta there's a very light orange hue left on the bottom of the dish and that's, to me, the hallmark of a great pasta sauce. You can taste each ingredient separately and yet they are harmonious at the same time, like tasting a good jazz recording.
Note: I left out a couple of my secret ingredients. It's taken me a while of constant testing and tinkering, giving out jars to people to get feedback, etc. to arrive at this recipe. I did it with no base recipe to start, and I'm proud of my marinara. So that said, I'd like to keep the full recipe "mine."
I still have to try adding a small amount of Marmite to it; I think the umami factor would be great.