A common misconception in the grocery aisle is that brown eggs are healthier than white eggs. In reality, there is no nutritional difference. The color of the egg shell is determined solely by the breed of the chicken. Generally, chickens with white feathers and white earlobes lay white eggs, while those with reddish-brown feathers and red earlobes lay brown eggs. The reason brown eggs are often more expensive is because the breeds that lay them tend to be larger and require more feed, making them costlier for farmers to raise. Inside the shell, the yolk color is influenced by the chicken's diet; a diet rich in carotenoids (like corn or marigold petals) results in a darker orange yolk. The shell itself is composed primarily of calcium carbonate.