I almost forgot one: it happened to a jeweler friend, who grew up near the Kingman Mines in Arizona. His father had some petrified logs on his land, so my friend had cut and polished a slice to make himself a really outstanding agate-topped coffee table. He built the wooden table, and then was going to glue the petrified wood slice to the wooden top. He spread one side with what amounts to super-strong crazy glue--and then absent-mindedly leaned on it, palm down, the way you lean on a table-top. Then he realized what he had done. His wife had to drive him to the emergency room with a 50-pound slab of agate crazy-glued to the palm of his hand.