Humpty Dumpty. Turtle eggs. Chicken-or-the-egg. You practically need a damp rag to wipe up the egg that's all over this book.
The kids themselves are all little eggs, just like Ethan imagines parts of himself "curled up like the turtle hatchlings newly emerged from their eggs" ("Ethan".258). They all have hidden gold nuggets inside them, just like the "best friendship" lying inside Nadia ("Nadia").
Remember too that Mrs. Olinski introduces them—and this is probably totally embarrassing to then, by the way—as prepubescent: "To her four sixth-graders puberty was something they could spell and define but had yet to experience" (1.4). Tender little prepubescent eggs, just waiting for the little turtles to emerge. Awesome.
And there's also the question of origin: "Logic," Grandpa Nate Gershom whispers at the crucial moment in the final match of the Academic Bowl, "tells me that an egg would come from a mother and a goose" (10). (Or a mother and a turtle, maybe.)
But here's the most important thing about eggs: They defy logic. An egg is more than the sum of its parts, because it's a thing in itself—an egg—but it comes from something else (a chicken) and is going to turn into something else (also chicken, unless it ends up in an omelet first). If you look at an egg and wonder which came first—well, according to The View from Saturday, you've totally missed the point.