Junior is a Maxis-made cell found in the Cell Stage at Level 5. They hatch from Maa's eggs and are Paa's children.
Juniors attack in groups and in the second half of Level 5, they show to be the only aggressive prey-sized cells, other than the player, which makes them immune to Spikes. A good way to counter them (and progress easily in the case of carnivores) is to have the poison part or electric part. They are known to eat everything, even dead Maas. They spawn when a Maa lays an egg, or a Maa dies. A good strategy is to electrocute them then run away while it charges. They die instantly to any attack, so the Poison weapon is extremely effective against swarms of them since it can kill them en masse while you run from them.