Kazachstania yasuniensis is a teeny-tiny living thing that is so tiny you need a microscope to see it! It is a type of fungus that lives in a place called Yasuni, which is a really special rainforest in Ecuador.
Now, Kazachstania yasuniensis is not like the mushrooms that you might see growing in the backyard or on a pizza. It is special because it has something called "yeasts" inside of it. Yeasts are tiny creatures that help make things like bread rise and beer ferment.
Scientists think that Kazachstania yasuniensis is important because it might have some really cool uses in our world. For example, it might help us make better medicines or find new ways to clean up pollution. So, even though it's really small and hard to see, Kazachstania yasuniensis is pretty important!