As the colony crystal moved south, so did the greater knightworm. Like the colony crystal, they had difficulty initially penetrating their new polar environment due to a lack of food, and like the colony crystal, they adopted an annual life cycle. Their eggs lie dormant until spring arrives. These eggs hatch at the same time as the southern colony crystals' spores germinate. Larvae are very small and cannot survive large southern colony crystal mycelial networks due to them being digested by the enzymes produced by the aforementioned colony crystal. Therefore, larvae will feed on young mats of colony crystal. This breaks up the labyrinth of southern colony crystal that has come to dominate Darwin Polar Coast. As they grow larger, they become resistant to the enzymes of the southern colony crystal, allowing them to traverse mature mycelial networks. As the summer progresses, the southern knightworm will continue to eat away at the networks, creating disturbed patches of southern colony crystal where the entire mycelial network is consumed, with only the crystals remaining. The colony crystals themselves typically survive such an attack, but take some time to regrow their mycelial network. Because of this, the southern knightworm must constantly migrate in search of more food.
As the summer comes to a close, and fall begins, the southern knightworm will begin to mate. Typically, they will mate in a grazed portion of the polar coast, where the mycelium won't digest their eggs. The mycelium will not grow back either, as the southern colony crystals have shifted their use of nutrients from repair to reproduction. After reproducing, most southern knightworms will die of exhaustion. The few that survive will continue to feed and reproduce until they too meet the same fate. When winter arrives, the sea floor will be covered in patches of southern knightworm eggs, which will be covered over the winter by a layer of corpses, providing warmth and cover for the eggs over the winter.