Hextherma
Hextherma diverges by developing a hexagonal shape instead of the ancestral octagon, making it possible to spread into a continuous tessellation without gaps. Its other main change is spreading in range. Instead of specializing on the large and stable vents in the LadyM rift, they will find any hot spot in the ocean depths where sulfur is produced. (These are volcanically active spots on the ocean floor that grow into seamounts.) Because most of the ocean is barren to them, they can now enter a dormant state in which they may exist inert for centuries. They will only become active once they find a hot spot. They are unable to tolerate oxygen but can go dormant when they come in contact with it too.
In their dormant state, ocean currents carry them far and wide across Sagan 4's oceans, even allowing them to reach the Vailnoff Ocean, providing a foundation for a chemosynthetic food chain. Once active, their rapid binary fission allows them to colonize whatever little hot spots they reach.
They are otherwise similar to before, with thick cell walls, an orangish tint from metabolizing sulfur, and the ability to grow cone-like structures en masse.