Why don’t birds lay ‘square’ eggs?

What’s the most common egg shape? Why are they shaped that way? And why don’t birds lay cubed eggs? Joe Hanson explores the science behind eggs and their shapes in this puntastic episode of It’s Okay to Be Smart. He explains:

What is “egg-shaped” even? I used to think it was the shape of a chicken egg. Then one day I saw a collection of eggs from lots of different bird species, and I realized just how many different kind of egg shapes there really are! I had to know why. And it turns out a couple teams of scientists had wondered the same thing. Here’s what science says about why eggs are egg-shaped, if that’s even a thing, which I’ve learned it might not be. Evolution of bird eggs, go!

Also, can you actually stand on two dozen eggs without breaking them? Hanson attempts to find out:

We also recommend the wonderful book The Book of Eggs: A Life-Size Guide to the Eggs of Six Hundred of the World’s Bird Species.

Plus, be sure to watch these videos: The Guillemot egg, an egg that saves its own life, The Field Museum’s amazing egg collection, and How Birds Get Oxygen Inside Their Eggs.