"I figured out-all by myself-that rock either formed much faster than I'd been told, or the scientist-who-knew-everything didn't know as much as they thought!"
How dare you question the all knowing all powerful Wizard of .. err Scientists!! ;)
We also had a huge sandstone boulder in a pasture at the top of a hill. Nothing remarkable about a big rock- except that this one was composed entirely of small marine animal shells. We called it the cheerio rock because that's what they looked like. I might have been a dumb farm kid, but I was smart enough to know there weren't any oceans close by and nobody was dumb enough to cart that boulder from the nearest salt water to it's current position!