Turtles

A well-known scientist (some say it was Bertrand Russell) once gave a public lecture on astronomy. He described how the earth orbits around the sun and how the sun, in turn, orbits around the center of a vast collection of stars called our galaxy. At the end of the lecture, a little old lady at the back of the room got up and said: "What you have told us is rubbish. The world is really a flat plate supported on the back of a giant tortoise." The scientist gave a superior smile before replying, "What is the tortoise standing on?" "You're very clever, young man, very clever," said the old lady. "But it's turtles all the way down!" -Stephen Hawking

Russell was indeed implicated in a famous tortoise-stacking  anecdote, as readers of Logicomix know. There's an elephant involved too, in his autobiographical postscript and in his discussion of the First Cause Argument for the existence of God in "Why I Am Not a Christian":

If everything must have a cause, then God must have a cause. If there can be anything without a cause, it may just as well be the world as God, so that there cannot be any validity in that argument. It is exactly of the same nature as the Hindu's view, that the world rested upon an elephant and the elephant rested upon a tortoise; and when they said, "How about the tortoise?" the Indian said, "Suppose we change the subject." The argument is really no better than that. There is no reason why the world could not have come into being without a cause...

Anyway, I bring it up because this is Bring Younger Daughter to Work Day, and she says she wants to talk to my students about turtles.
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POSTSCRIPT: She came, she quizzed two classes and plied them with candy (in recognition of Presidents' Day), and was surprised at how many college students didn't know that Dr. Seuss wrote "Yertle the Turtle" or that John Glenn orbited the earth 50 years ago.