A newly hatched animal which has not developed all its body parts is a Nymph.
A nymph is the immature form of some invertebrates, particularly insects, which undergoes gradual metamorphosis before reaching its adult stage. A group of mammals that lay eggs and their young are hatchlings as well known as monotremes. Fish, amphibian, reptile, or bird are hatched in oviparous biology.
a theory is usually supported by evidence or another laws rules. it must have pretty strong evidence, but it can NOT become a law. a law is set in stone, and proved by math.