Larva
Definition: An early, immature stage in the life of many animals that looks very different from the adult form, such as a caterpillar or a tadpole.
In simple words: A young animal that has not yet changed into its adult shape.
More about larva
Many insects, amphibians, fish and marine invertebrates pass through one or more larval stages before changing into adults, a process called metamorphosis. The axolotl is unusual because it typically keeps larval features, such as external gills, into adulthood.
Also called: Larvae (plural)