Question

how egg come on Earth
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Answer 1

Explanation:

The first eggs

These first came on the scene with the evolution of the first amniotes many millions of years ago. Prior to their arrival, most animals relied on water for reproduction, laying their eggs in ponds and other moist environments so that the eggs didn't dry out.

Answer 2

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So proto-hen laid an egg, and proto-rooster fertilized it. ... So in a nutshell (or an eggshell, if you like), two birds that weren't really chickens created a chicken egg, and hence, we have an answer: The egg came first, and then it hatched a chicken