Must have been one heck of a cataclysm to lower a 35 m pyramid 500 m underwater.
Turned an "outie" to an "inny"?
The Gulf of Mexico in the Yucatan area is supposed to be a meteor crater. That would be a large enough cataclysm. But that was many many moons ago. The time line likely doesn't fit.
I used to wonder why geodes were turning up in Tampa Bay.
Fla. is a big limestone rock with no volcanic past of which I'm aware.