1. Eggshells have up to 17,000 microscopic breathing holes. Although an eggshell looks completely solid, it is covered in tiny pores made of calcium carbonate crystals. These invisible vents allow oxygen to flow into the developing chick and let carbon dioxide and moisture escape!

2. An ostrich egg is equivalent to about 24 chicken eggs. Ostrich eggs are the largest laid by any living bird, weighing over 3 pounds each! The shell is so thick and strong that an adult human can stand on top of one without cracking it.

3. Earlobes reveal what color eggs a hen will lay. You can often guess the color of a chicken's egg just by looking at its earlobes! Hens with white earlobes typically lay white eggs, while hens with red or brown earlobes usually lay brown eggs.

4. Not all mammal babies are born live—some hatch from eggs. While most mammals give live birth, a special group called monotremes lay soft-shelled eggs instead! The platypus and the echidna (spiny anteater) are the only living mammals on Earth that hatch their young from eggs.

5. You can tell if an egg is raw or hard-boiled by spinning it. If you spin an egg on a flat table, a hard-boiled egg spins fast and smoothly because its insides are solid. A raw egg wobbles slowly and stops quickly because the liquid yolk and white slosh around inside!

6. Fresh eggs sink in water, while old eggs float. As an egg gets older, the tiny air pocket inside its wide end expands as moisture evaporates through the shell pores. If an egg floats in a bowl of cold water, it means the air pocket has grown big enough to make the egg buoyant!

7. An egg yolk's color depends entirely on the hen's diet. A rich, bright orange yolk means the chicken ate foods high in yellow-orange pigments called xanthophylls (found in yellow corn, marigold petals, and green plants), while a pale yellow yolk means a diet of light-colored wheat or barley!