I know, I know. This comment certainly topped our "oddest things ever uttered in our house" list. So we asked her what she meant.
"See?" she said. "I have an upside-down grandma in my belly button. Her eyes are closed. You can see her hair, eyes, cheeks, nose and mouth."
So we took a look. This is what we saw:

We still weren't exactly sure what she meant, so Seth came up with the idea of taking a closeup of the kid's midsection, printing it out and letting her draw the grandma on there. Here are the results:
(The picture has been flipped so you can see the grandma right-side-up.)And in case you're still having trouble seeing it, here is a diagram:

I don't know whether to be amazed at her imagination or worried that she spends so much time analyzing her umbilical cord stump. Either way, she's a cutie.