A long time ago, there were scientists that understood earths geology. at one time, they wanted to explain this to uneducated people, who were scared by earthquakes and volcanic activity.
they talked about solid plates and the softer molten layers underneath. and they tried to explain the earthquakes and volcanic activity were caused by the moving of the plates. but the uneducated people didn’t understand. they had animist, not scientific thinking. animism requires a conscious being to be the cause of everything and that conscious being must be in the form of a higher life form. rocks just don’t cut it for animism.
so the scientists used a comparison. they said that the earths surface is like the back of a giant tortoise.
the uneducated animists smiled. they could understand. the idea of a living creature totally fit their animist prerequisites. immediately they transplanted “like” with “is” because thats what suited them – just as humans still constantly do today. they spread the word to other animists that the world IS on the back of a giant tortoise.
and it was settled.