I've seen a turtle climb onto a turtle before, but never a turtle climbing onto a turtle who was on top of a turtle... I don't think they can reach that high.
That said.... if there's a turtle on top of a turtle, and then another turtle bumps into them, then a fourth turtle could climb on one turtle, climb on top of both turtles, and then there would be three turtles on top of each other!
|
|O
|OO
|OOO
Turtle pyramid!