Eggs
The eggs we scramble and fry typically span a humdrum range of colors, sizes, and shapes. But the avian kingdom lays eggs of vast variation. When it comes to shape, biologists have long wondered why, say, murres have pointy eggs, yet ostrich eggs are rounder. Aristotle suggested males come from rounder eggs, and others suggested elongated eggs wouldn't roll off cliffs. In a recent study, researchers finally cracked the case by examining some 50,000 eggs from 1,400 species. They found no nesting habit links, but did see a pattern correlating with flight ability. Frequent fliers, like murres, have streamlined bodies and more elliptical eggs, while birds who like their feet on the ground – say, ostriches – have rounder ones. So overall it's the bird that shapes the egg, forever proving which comes first.