On a school field trip to the C&O Canal, we stopped inside a stone block tunnel built during that portion of the canal's construction in the early 1800s.
With a completely straight face, the area's preeminent science teacher told us to look up at the stalactites hanging from the ceiling and proclaimed that it “took millions of years for them to form”.
Even at the age of 10, my BS detector went off.
LOL. :-)