|MadSci Network: General Biology|
The egg shell provides mechanical strength to the eggs. This protects the chick inside the egg and permits the parents to move (turn) the eggs and to sit on them. The shell is a porous material, mainly calcium carbonate. It covers the two membranes surrounding the egg white -- the inner and outer shell membranes -- these are the materials that provide the anti-microbial protection. The shell is created in the oviduct after all the other stages of the egg are assembled.
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