Sexual maturity
there are many Species that can develop and form Eggs that contain the placenta inside which then helps the offspring develop inside the egg 20 0r 21 eggs in bird species such as poultry or waterfowl. in other species like insects and marine life, the animal can produce a random amount of eggs oftentimes more than one. It is oftentimes that eggs of certain marine species have a slim chance of survival, probabilities being 1 in 500 that an egg hatches and grows into a fledged out adult specimen.