Back in the early 80’s, our outfit introduced our first low-power CMOS microcomputer.
Somebody got the idea of powering it with lemons. They stuck a copper electrode and a zinc electrode into a lemon, and then put two or three of these in series, giving enough voltage and current to run the micro and an LCD displaying the time of day.
They showed it off at a couple of electronics conferences, and then our marketer brought it back to the office in a plastic box and stuffed it under his desk.
A month or two later when he dredged up the box, the lemons were all moldy and LCD was blank. But he squeezed the lemons, and lo! it sprang back to life, and had actually been keeping time the whole while.
Then there’s the hamster-powered clock whose software I wrote, but that’s another tale.