As the beach knightworm ventured further inland, it found it harder to survive. With no colony crystals to control the growth of their exoskeleton, their exoskeleton overgrew and killed those that ventured too far inland. However, some individuals found what would become their savior: the dwarf mycostrum. When some spores landed on the beach knightworm’s exoskeleton, it began to grow over it, feeding on the ever-growing exoskeleton. This kept these beach knightworms’ exoskeleton in check, which allowed them to live further inland. Over time, this inland population of beach knightworms evolved into the mycostrum knightworm.
The mycostrum knightworm has adapted to accommodate the mycostrum that grows on its segments. Most of the spikes have been lost to provide more living space. Its ventral spikes have grown larger to provide better traction as it inches along the forest floor. Its spiracles can now be shut, greatly reducing water loss and allowing it to live on land indefinitely. Its purple coloration allows it to blend in with the mycostrum patches it often inhabits. Its behavior has changed little from its ancestor. It feeds on soft mycostrum mats, ripping chunks off with its antennae, and will travel great distances to find them. Like their ancestor, the mycostrum knightworm requires water to reproduce. With no body of water nearby, the mycostrum knightworm will mate in puddles, leaving behind rapidly-developing eggs that will hatch in a few days' time. Because of this, the larvae are only a millimeter in length and will feed on detritus to survive.