Snowmelt Wormoss

Southern wormoss spread further south and inland in the small continent of Fermi. It remained bound to the water for reproduction, as its gametes needed to swim in water to find and fertilize each other. However, in this cold, seasonal environment, they found a new available venue: snowmelt. During each year's spring thaw, they would spawn at the same time, and the gametes would find each other in puddles of snowmelt. Fertilized eggs would form into juveniles, which would spread out, subsisting on detritus, supplemented by photosynthesis, growing over the course of a year. In the next spring thaw, these juveniles would release sperm into the snowmelt, then find a place to settle down and grow into a mature, sessile adult. Adults could live for several years and would produce both sperm and eggs.

The newly developed snowmelt wormoss was still unable to spread into areas that drained very quickly, but Fermi was fairly flat, with little rugged terrain, so they were able to spread to many inland areas. They could still reproduce in permanent water, so they'd be found in riparian areas and on beaches as well.

Given the instabilities of the weather, adults were often being knocked over, buried under snow, or swept away by floods. Rather than evolving to anchor themselves, like their wormwort cousins, snowmelt wormoss instead retains some of their musculature and mobility into adulthood. They still lose most of their nervous system and the ability to make mucus, and the adults can't crawl around, but they are able to orient themselves. This is also useful for making sure that they face the sun in its low position on the north horizon. They can also adjust based on how crowded their area is. If there are no others nearby, they can spread out mainly horizontally, while if there are more nearby, they'll stretch upward on either end. This flexibility helps them live longer than their ancestor, as they can reemerge each year after the winter.

The adult leaf-thorns have become even more similar to conifer needles in form and function. The funnel has also narrowed, as it was too likely to cause the whole organism to get knocked over if it filled with snow.

Otherwise, snowmelt wormoss is much like its ancestor. They have a segmented chitinous outer shell, capable of photosynthesis, and a soft inner core that contains their organs. These two parts come from genetically distinct cell lines, formed from the separate parts of their two-cell gametes. Juveniles secrete mucus to move around, and they have a pair of light-sensitive patches in front of each gap between their segments, which fade upon adulthood. Both juveniles and adults breathe through spiracles in the gaps between each segment. Juveniles have a digestive tract running throughout the whole body, which redevelops into a series of vessels in adulthood that transport nutrients and water throughout the organism.