Wow, hearing about “tea mushroom” (that’s how it’s called in Ukraine) for my whole life, and it’s not a mushroom!

Fascinating.

Well, it is a partly a yeast, which is a fungus, as are mushrooms. The main thing is that it is a symbiotic combination of particular yeast and bacteria strains, unlike what is used for brewing alcoholic drinks (just yeast) or fermenting dairy into yogurt (just bacteria).

Kefir is another combination of yeast and bacteria, though different strains.

It’s called a scoby