The life cycle goes

Baby Crewmate: A small infant that is dependent on its parents.

Crewmate: Similar in appearance to its previous form, its eye shrinks due to more sun exposure

Moonbase Alpha Astronaut: As it prepares to enter adulthood, it retreats to caves, communicating by singing. Its eye grows immensely.

Halo 1 Spartan: The most active stage in life, also the longest. It establishes territory and fights others at this stage. Very combat-oriented

Lethal Company Worker: The "elderly". Responsible for scavaging resources for the colony. Eye shrinks incredibly due to constant sun exposure.