As the Mycostrum Knightworm moved further north, when evolving into the Fur Knightworm it changed very little at a glance. However, this is because of the evolution of its symbiote which it carried with it preventing it from needing to change much when it entered the colder temperate regions. The exception is the new necessity to hibernate over the cold winters, which it is still not equipped to handle otherwise.
The Fur Knightworm is named for its symbiote, the Fur Mycostrum, which has developed insulating fibers derived from degenerate fruiting bodies specifically to help its host. This benefits both, as it allows the Fur Knightworm to survive in cooler environments and therefore continue to provide the mycostrum with an overgrowing exoskeleton to feed on. The Fur Knightworm is still not an endotherm, as such a high metabolism is not justified by its diet and rate of feeding. However, the insulation combined with a more compact shape allows it to hold heat in more easily, letting it stay active in early spring and well into late fall. When winter arrives, the Fur Knightworm uses its modified antennae to dig a burrow where it hibernates until spring. Its rate of exoskeleton regeneration slows down during this time to conserve energy, and the Mycostrum symbiont likewise slows down its own metabolism to survive over this time period so that the Knightworm won’t need to find a new symbiont when it awakens.
The Fur Knightworm is otherwise like its ancestor. It depends on water to reproduce, so it mostly mates and lays its eggs in the spring in summer when there is lots of rain to create puddles. Its eggs are fertilized externally and develop rapidly, resulting in tiny 1-millimeter larvae that rely on detritus to survive. Young Fur Knightworms must obtain a Fur Mycostrum symbiote before winter arrives, as they will freeze to death otherwise; fortunately, as Fur Mycostrum is also their primary source of food, this is not difficult.