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xVA9B TIL that the 365-day calendar we use today was invented by the ancient Egyptians.
JYgK4 TIL it is currently the year 4716 in China.
PYEAg TIL that azurite was commonly used as a blue pigment in middle age and Renaissance paintings, but it oxidates at some point and turns into malachite. So the blue parts made from azurite in those paintings are now green.