Ask A Scientist© Biology Archive

How is an egg shell formed?
Tim

Answer:
Egg shells are formed by a complex interaction between a mother
and her developing embryo(s).  There are several layers in an
egg shell, each with a different function.  The outmost layer,
what we usually think of as the shell, must protect the embryo
and allow the passages of certain gasses (so that the embryo can
breathe).  Different egg shells are made from slightly different
materials; notice how a chicken egg is much more rigid than, say,
a snake egg.
Hope this helps you, Tim.
Ethan Allen