Algae
NeoEdiacaran Protist descendants:
Large Colonial Choanoflagellates
Similar to Earth pyrosomes, these protists form large amorphous colonies roughly resembling tubes. Living in the open water without a lot of competition, they've quickly become a cosmopolitan species. Benthic forms also exist on sandy bottoms, feeding on tiny organisms in sand.
Spongeroot
The Spongeroot is a descendant of the very successful kelp algae. For millions of years they had grown relentlessly with nothing stopping them, even spawning smaller tropical varieties. The evolution of herbivorous Ephyrazoans did eventually control their populations but did not stop their radiation. Thus, the Spongeroot had evolved. An amphibious algae living in rocky coasts that had evolved something like a plant's vascular system. The holdfast has evolved a hollow chamber inside, storing minerals and water for the protist's nutrition and stem building. Everything besides the leaves are covered in a layer of calcium carbonate, gathered from tide water and crashing waves. Shorter species have cells lined with cilia within their chambers for water transportation, while taller species evaporate water within their chamber to transport it upward. Both methods work well but the latter is less energy intensive and converges on terrestrial plants. Reproduction occurs similarly to their ancestors, spores are dropped into the surrounding water or pulled off by wind. They start fully submerged then grow out of the water to consume the most sunlight possible.
Spongeroot Diversity
Spongeroots have diversified into many forms over a few million years, most becoming more terrestrial due to a lack of competition and abundance of fertile soils. All groups descended from the Spongeroots grow zoospores and gametophytes directly on the plant body and in the case of the Pom Pom, have formed the early Sporophyte stage into the perfect shape for catching wind and travelling long distances. Terrestrial and freshwater kelp have far less calcium carbonate in their stems in exchange for hardened smooth cellulose.
• The Pom Pom Kelp is the dominant life form in the Northern hemisphere, many growing several meters tall and forming temperate forests. Due to colder temperatures, their leaves are thinner like pine trees. The holdfast has adapted it's cilia covered vascular cavities into elongated tubes that grow outward to find water inside their substrate. They still possess a hollow oasis chamber inside, though now it's built to store more minerals than water. This was an important adaptation for all Spongeroot descendants that moved away from marine habitats due to lack of salt content in soil.
• Fuzz Kelp have reduced the stem entirely to fill niches analogous to moss and lichen. They grow on any surface where water is present, using the flattened holdfast to encrust onto rocks and kelp bark. This segment of the algae has also minimized the intake holes significantly to prevent creatures and fungi from stealing it's mineral supply. The cilia have also been reduced, in a terrestrial environment humidity and rain is enough to sustain them.
• Twizzler Kelp is the most similar to its ancestors. A ciliated vascular system still draws in water, though it also expels it. The Twizzler Kelp uses it's suction to gather as many salts as possible in a similar manner to how fish and motifers deal with osmosis. This group is exclusive to colder environments since mangroves have taken their niche effectively in tropical areas.
Rhizophorean Protist descendants:
Kacti
Kacti are terrestrial spongeroot algae adapted for one of the harshest environments, hot and cold deserts. Waxy leaves, thick stems, lengthy roots, and defensive spikes are all necessary adaptations for Kacti to properly live with little water, hot temperatures, and voracious herbivores. Kacti have also adapted the sporophytes to form on the the tips of their blades for maximum wind dispersal. To aid this further, sporophytes look like tiny umbrellas to be carried by the desert breeze. Terrestrial kelp have now started taking root in the southern hemisphere, some competing with mangroves by taking up smaller spaces that the trees had yet to fill.