How do eggs form inside of reptiles and birds?

Question

Also, how is it possible that sometimes inside a chicken’s egg there is another smaller egg..?

In: Biology

Answer 1

It’s simply like the birth egg off a chicken (female) with a calcium shell (if I’m correct), which can be fertilized by a rooster, which creates the living chick inside, which the egg is literally like the womb of a mammal, so it’s the same proces but with a like egg with a protective shield around it