So, here's an idea for a sci-fi short story:
FACT: Sourdough is created by mixing a living starter with fuel that feeds it. The starter can (and has done, in some famous bakeries) live for hundreds of years. This is what I'm thinking: SENTIENT BREAD LOAF.
It's intent is something we are not yeasty enough to comprehend. Almost certainly malevolent, but probably tasty with jam.
http://www.exploratorium.edu/cooking/bread/recipe-berkeley.html Off to bake something....