A friend gave me a SCOBY for making kombucha (fermented tea). This disc that forms on top of old tea (a Symbiotic Colony of Bacteria and Yeast) looks like one of the flying rubber-pancake aliens on the Star Trek: TOS episode, "Operation: Annihilate!" one of which attacks Mr. Spock in a scene which Red Bear reenacted on my back porch. Motel plays Capt. Kirk:
SEE also other toy tableaux
I used the SCOBY afterward, and it worked just fine.
Super easy--don't even need a recipe:
you just plunk it into room-temperature black or green tea w/sugar, cover it with a cloth (to keep out bugs), and let it sit for a week or so. It'll start to smell vinegary. You can add fresh ginger and the like after it's fermented, if you want, and let sit a little longer for flavor. I like it plain just fine.
It does become slightly alcoholic, if that's a concern. (Not sure how much... I don't notice it myself.)
A new SCOBY forms---save them both with a little of the kombucha for the next batches. Soon you will have a colony to share with your friends or make sci-fi movies with.