I'm sure most have seen this and maybe it was posted here before but I laugh every time I think about this .... http://www.talkorigins.org/faqs/coso.html
That reminds me of the sparkplug I found while snorkeling near La Paz in Baja some years ago. It had been used as a sinker for fishing and got away. It was badly caked with minerals, but not quite to the point of the one in the story. I chipped the excess mineral off so it was recognizable as a sparkplug.
Some time later, a Cuban guy brought me his Porsche 914 on a trailer. The pros couldn't fix it. When I found the broken ground wire to the EFI, I pulled that plug out and said, "Here's your problem."
He about swallowed his teeth. He gladly paid the modest amount I charged and later brought me a special bottle of Cuban booze. I don't drink, but I'm sure wifey made use of it.
Too bad I didn't take pix of the plug, but that was before digital cameras.