Answer:
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.