Which animal produces a hard shelled egg that matures outside the mother?

Answer;

-Bird.

Explanation;

-Birds reproduce by internal fertilization, during which the egg is fertilized inside the female. Birds have cloaca, or a single exit and entrance for sperm, eggs, and waste.The sperm from the male is transferred to the female when they touch cloaca, an act referred to as the cloacal kiss.

-Birds' eggs get fertilized inside the female bird's body, before the shell is formed. Then each egg comes out before any development of the fertilized egg starts.