The Kombucha Mushroom is not a true mushroom but pseudo lichen. It is a fibrous cellulose spongy membrane that is formed by the various Kombucha bacteria and yeast cells that live in the liquid sugary tea. It is primarily grown to act as an evaporation cap to keep the tea from evaporating and also to prevent other microorganisms from getting to the sugary tea. It has no sex, and produces no seeds or spores for the purpose of reproduction, but within the cells of the membrane are contained the same bacteria and yeasts cells that exist within the tea. When added to a new batch of tea you introduce these bacteria and yeasts which quickly colonize it, cause the tea to ferment.
Kombucha tea is safe to drink and even the Federal Drug Administration has indicated it is safe provided it is prepared in a clean manner like any other food or beverage you are planning to consume. Millions of people drink Kombucha daily and see positive benefits from doing so. A lot of people pose the safety question about Kombucha because they mistakenly believe it to be a mushroom and they are aware that some mushrooms are poisonous. Kombucha is not a mushroom; it is something more like lichen, a simple plant.