Southern Wormoss
Southern wormoss developed as wormoss spread southward into the temperate zone. The adult form changed little; they have a larger number of segments, each segment smaller than before, and as each segment still bears a pair of leaf-thorns, this means a substantially larger number of leaf-thorns. Furthermore, the leaf-thorns are narrower but spread out more, more needle-shaped. As a result of these adaptations, there is a larger area exposed to sunlight at a wider variety of angles, adapted to the lower position of the sun. They also deal better with snowfall, providing less of a surface for snow to accumulate. The narrow leaf-thorns also retain water better, useful in areas with more seasonal variation in precipitation.
The biggest change is to their lifecycle, however. The juveniles are now fully capable of travelling across the land. Their chitinous outer shells close over the inner core, like in the adults, but they have developed tiny holes where the segments meet, which can open and close to breathe. At the base, the soft core extends between the segments as a muscular foot, which lets the juvenile slowly crawl forward. The base also secretes mucus, providing a slimy trail that makes it easier for them to slide around and which covers the soft parts inside the shells, keeping them hydrated. They cannot venture into dry regions, however, as they must consume large amounts of water. They also have light-sensitive patches growing at the top of the joints between the segments, making it easier to navigate their environment; these fade upon adulthood.
As a result, the juveniles are able to cross Fermi to spread from coast to coast and are able to spend more of their life gathering food from the land, in the form of decomposing flora (including dead members of their own species). Once they find a place to settle, the adult curls upward and becomes immobile, growing rapidly, adding new segments at their base. The life cycle is seasonal: They usually settle in the springtime, as sunlight becomes more available. Most southern wormoss adults only survive a single year, dying in the winter, but some lucky individuals make it through to the next. Juveniles are, therefore, a proportionately longer part of their lifetime. The juveniles have a simple system of nerves and muscles, which they also reabsorb as adults. The juveniles have a digestive tract that runs throughout the soft inner core. The mouth and anus both consist of a small opening in the shell, with muscular flesh inside, useful for grabbing food or pushing out waste. At the mouth, the flesh can mush the food together, but they are unable to ingest or process anything hard. This digestive system is repurposed into a system of vessels that distribute water and nutrients, and the mouth grows a funnel that collects rainwater.
They remain bound to water for reproduction. Juveniles start producing sperm fairly early; adults produce both sperm and eggs. Sperm and eggs consist of two cells, one to produce the soft core and one to produce the shell, which are genetically distinct. Sperm and eggs can only travel through water, so they must be released in the tidal zone or areas where the rain will wash them into the sea or gather them together in puddles. Therefore, although they can grow some way into the temperate forests, this is limited to the moistest spots.