OK, I'm not quite sure what the episodes' names are. On the episode where Lisa wants to go see the Egyptian area in the museum and gets lost but Homer takes her there at the end, they look at something called the Sphere of Isatopa. In the episode where the Simpsons fall asleep in church, wait until the Lisa dream, and when she and Milhouse get trapped in the pyramid (just after Chief Wiggim says "give my regards to the British Museum") look from the middle to the right hand side of the screen, overlapping them, slowly moving off screen when they're walking, is that Sphere of Isatopa.