Cracking the Mystery of Egg Shape by Jia You, Sarah Crespi, Science Magazine

Every egg rolls a different way. For centuries, scientists wondered why egg shapes are so different from one bird to the next. Now, we think we’ve finally cracked the mystery.

To start, we need to know what egg shapes are even possible. Luckily, hobbyists and natural history museums have been collecting and cataloging bird eggs for hundreds of years. Then, what kind of birds are linked with the different shapes? And finally, how might their special traits—from nesting habits to body size—change the shape of their eggs over evolutionary time?