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What is an egg, anyway? Defining the parts of an egg

Have you ever wondered about the individual parts of an egg? Well, I’m about to drop some knowledge on you. Eggs may seem simple, but once you start to learn more about them, you’ll realize just how fascinating they are.

A bunch of eggs, one of them is cracked open.

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Eggs are among the most consumed food items in the world, but have you ever stopped to think about the distinct parts of a chicken egg? Whether you’re a foodie, a farmer, or just an egg enthusiast, once you learn about all the parts of an egg, you’ll understand why I created a whole blog about them.

What Are the Parts of an Egg?

Let’s start with the basics: What is a chicken egg, anyway? A chicken egg is a reproductive product of a female chicken or hen—it’s how a hen creates a new baby chicken. However, most eggs are laid for consumption rather than hatching into chicks. An egg is made up of several parts.


The bloom (also known as the cuticle) is a natural coating on outside of the eggshell that prevents bacteria from entering the egg. It is made up of tiny pores and a layer of wax, which seals in the egg’s moisture and keeps it fresh.


The shell is composed mostly of calcium carbonate. It provides a protective barrier for the contents inside the egg, and also plays a crucial role in maintaining the egg’s freshness.


The membrane is a thin, translucent layer on the inside of the eggshell. It helps to protect the egg from bacteria and other contaminants, and also provides a barrier for the developing embryo.

Air Cell

As an egg ages, it loses moisture, which causes its contents to shrink slightly. This creates an air cell at the rounded end of the egg. The size of the air cell can help you determine how fresh an egg is. The bigger the air cell, the older the egg.

A bunch of eggs, one of them is cracked open, with a whisk.


Also known as egg white, the albumen is the clear, viscous liquid that surrounds the yolk. It is made up of water and protein and serves as a source of nutrition for the developing embryo. When cooked, the albumen coagulates and becomes solid.


The chalaza is a pair of thick, twisted strands located at either end of the egg. They help to anchor the yolk in place and keep it suspended in the center of the egg.


The yolk is the yellow, spherical object located in the center of the egg.  The yolk usually accounts for about a third of the egg’s total weight, but it contains most of the nutrients. When actually growing a baby chick, the yolk is the embryo’s food supply and provides a rich source of protein and fat. When cooked, the yolk becomes solid and develops that classic yellow color.

Fun Facts About Chicken Eggs

Now that we have a basic understanding of what makes up a chicken egg, let’s take a look at some fun facts that you may not have known before:

  • A chicken eggshell has around 17,000 tiny pores on its surface.
  • Different chicken breeds will lay different color eggs. Some breeds lay white eggs, while others lay brown or even blue or green eggs.
  • The average chicken lays around 250 to 300 eggs per year. That’s a lot of omelets!
  • According to the Guinness Book of World Records, the largest chicken egg ever laid weighed in at 16 ounces (that’s a whole pound!). That’s nearly eight times the size of a typical egg (a large egg usually weighs around 2 ounces). This whopper had a double yolk and a double shell and was laid by a white leghorn hen in New Jersey in 1956.
  • More than half of an egg’s protein — about 6 grams for a large egg — is in the white.
  • The protein in chicken eggs is the most complete protein of any food in our diet — it has all of the amino acids we need, and in the right proportions, too.
  • Eggs contain high doses of heart-healthy omega-3 fatty acids in the form of DHA.
A pair of hands holding a cracked open egg over a bowl.

The Final Word

There you have it, folks! Whether you prefer your eggs scrambled, fried, poached, baked, or boiled, there’s no denying the importance of this little oval-shaped wonder in our diets. So go ahead, crack open an egg and enjoy!

By on March 4th, 2023
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About Robin Donovan

Hi, I’m Robin! I am a full-time food blogger, recipe developer, and cookbook author. I spend my days cooking, writing about, and photographing food.

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