You may be asking about domestic chicken eggshells, of kinds of eggs we most often find in out kitchen. However, many animals lay eggs with protective shells, including birds, reptiles and the egg-laying mammals, such as platypuses. Other animals such as amphibians, fish and insects also lay eggs. Most amphibian and fish eggs have no eggshell and may have very thin, transparent outer layer. A few fish,like sharks and rays, may have thicker encasings of the developing embryos.

The common white color of the eggshells from vertebrates is due to the mineral calcium carbonate from which the shells are made. There are tiny pores in the shells of eggs to allow oxygen, carbon dioxide and moisture to pass through, but to keep bacteria out. The domestic hen's egg has between 7,000-17,000 pores.

Thickness of eggshells can vary depending on the species, the size of the egg, the age and health of the mother, what time of the year the egg is laid, what nutrients were available and the presence of certain pollutants, among other factors.

To understand the thickness of eggshells, it's a good idea to review very small measurements:

A meter is divided into 100 centimeters. Each centimeter is divided into 10 millimeters. Each millimeter can be broken into 1000micrometers. One micrometer (sometimes called a micron) is 1 millionth of a meter. Domestic chicken eggshells vary, but will be about 400micrometers, or 0.4 millimeters. A human hair is about 100 microns thick. Ostrich eggs are much thicker, about the width of a nickel, 2millimeters thick.

I hope that answers your question!

How thick an eggshell depends on what kind of egg you're talking about!A chicken egg is really thin. It's about 300 micrometers thick or 0.3 millimeters!! (A micrometer is 0.001 millimeters!) On the other hand, an ostrich egg is about 2 -3 mm. Ostrich eggs are much thicker than chicken eggs because the ostrich egg has to withstand the weight of an ostrich sitting down on it. A human can stand on an ostrich egg and it will not break.