The Early Stromacene

The Cyanophytes

From the cyanoreza came the earliest of what one might consider plant life on Atmos. These blue pigmented autotrophs rapidly became the dominant primary producers in the planet’s young oceans, forming the foundation of the marine food web. Their evolutionary success stemmed from a combination of efficient light absorption, adaptability, and the ability to anchor themselves to substrates, allowing the cyanoreza to spread across a vast range of aquatic environments-from sunlit surface waters to deeper, dimly lit regions where only trace amounts of Phanes’ blue light could penetrate. 

The cyanoreza underwent a remarkable diversification, giving rise to a variety of forms, from simple microbial mats carpeting the seafloor, such as Cyanomatis (Blue Mats) to tall, frond-like structures swaying in the currents. Some species evolved buoyant structures and lost their posterior holdfasts, like Cyancaputis (Blue Heads) allowing them to float freely in the open ocean, while others developed more complex root-like anchoring mechanisms, securing them to rocks and underwater cliffs, like Cyananexxis (Bound Blues). The cyanoreza all but monopolized the shallow coastal zones, outcompeting free-floating autotrophs that struggled against currents and grazing pressures.

As these early plant-like organisms spread, they transformed Atmos’s oceans, altering its chemical composition by releasing oxygen as a byproduct of photosynthesis. This shift in atmospheric and oceanic chemistry would have profound consequences, paving the way for more complex aerobic life forms to evolve.

The Membranutriors

Poremorphis

One lineage of membranutriors took on a crucial ecological role as detritivores, specializing in the consumption of marine snow, decaying organic matter, and other nutrient-rich detritus sinking to the ocean floor. These organisms, known as Poremorphis (Pore Forms), developed extensive, root-like structures that burrowed into the seabed, allowing them to absorb nutrients directly from decomposing organic material within the substrate. Much like fungi on Earth, poremorphs became vital recyclers within Atmos’s marine ecosystems, breaking down dead organic matter and returning essential nutrients to the environment.

Spreading across the seafloor in vast, interconnected networks, poremorphs formed dense, mat-like colonies that could cover entire stretches of the ocean bed, thriving in deep, oxygen-poor waters where other life struggled to survive. Some species evolved enzymes capable of breaking down tougher organic compounds, enabling them to process material that other organisms could not digest. Others developed specialized feeding adaptations, such as sticky or porous surfaces, which allowed them to trap and break down microscopic life that drifted too close. Over millions of years, the poremorphs diversified, giving rise to a range of specialized detritivores, from slow-growing deep-sea absorbers to fast-spreading microbial decomposers that flourished in nutrient-rich environments. Their success ensured that no organic material went to waste, making them a cornerstone of Atmos’s early ecosystems and a key driver of nutrient cycling.

Lithofloris

A distinct lineage of membranutriors took an innovative evolutionary path by forming symbiotic relationships with some microscopic autotrophs, mirroring the role of the zooxanthellae found in corals. These organisms, known as Lithofloris (Stony Flowers) became living partnerships between heterotrophic hosts and their photosynthetic or chemosynthetic microorganisms, cyanosymbiontis. This mutualistic relationship provided both organisms with distinct advantages-the cyanosimbionts supplied a steady flow of energy and nutrients through photosynthesis or chemosynthesis, while the lithoflora hosts offered protection and a stable substrate in which their symbiotic partners could thrive. 

As this partnership strengthened over evolutionary time, lithoflora evolved into intricate, reef-forming structures, with their autotrophic symbionts creating a living “skin” around the heterotrophic core. These composite organisms anchored themselves to the seafloor, growing into sprawling colonial formations that became hubs of biodiversity, much like Earth’s coral reefs. Their rigid, mineralized skeletons helped them withstand ocean currents and predation, further solidifying their dominance in shallow, nutrient-rich marine environments. As the Thalassian Era progressed, lithoflora expanded across Atmos’s oceans, constructing massive reef ecosystems that provided shelter and feeding grounds for countless other organisms. Their ability to efficiently capture and recycle nutrients made them a critical foundation of marine life, with their reefs eventually becoming cornerstones of oceanic life.

The Luranutriors

Serpostomis

One group of luranutriors took on the role of mobile detritivores, evolving into rolling, multi-mouthed scavengers that consumed decaying organic matter as they moved. These organisms, known as Serpostomis (Creeping Mouths) developed entryways across their entire body, allowing them to ingest detritus from all directions as they rolled over the seafloor. Their soft, asymmetrical bodies adapted to the uneven terrain of the ocean bed, ensuring maximum contact with decomposing material. 

To aid in propulsive locomotion, serpostomes evolved tentacular structures covering their surfaces, which helped them grip, push, and maneuver through sediment while simultaneously catching marine snow and suspended organic matter. This gave them an advantage over sessile detritivores, allowing them to actively seek out nutrient-rich patches of decay. Over time, some species specialized in consuming specific types of organic debris, from soft microbial mats to coarser remains of dead organisms.

Magtrogis

Another lineage of luranutriors took an evolutionary step back toward a sessile lifestyle, becoming anchored filter feeders that relied on passive feeding rather than active foraging. Magtrogis (Great Eaters) developed large, gaping mouths to capture the constant rain of marine snow and suspended organic matter drifting down from the ocean above. By securing themselves to the seafloor, magtrogs transformed into living nutrient traps, sustaining themselves on the steady influx of microscopic detritus. 

On Earth, numerous organisms have evolved a sessile lifestyle after a motile stage, such as corals, barnacles, and sea lilies. Many, like coral polyps, begin life as free-swimming larvae before settling onto a substrate, where they remain for the rest of their existence. Magtrogs exhibit a comparable life cycle, with their early planktonic stage playing a crucial ecological role.  In their juvenile form, known as Pipants, young magtrogs are released en masse from the mouth of a fertilized adult, dispersing into the ocean as free-floating larvae. Most Pipants will live out their entire existence in this stage, forming a significant part of Atmos’s planktonic ecosystem and feeding thousands of species. However, a select few will undergo fertilization, triggering their transformation into sessile adults. These individuals will anchor themselves to the seafloor, growing larger as they transition into the stationary “Magtroglodyte” stage, where they serve as permanent nutrient processors in the benthic ecosystem.

Ossacorpusis

In what would eventually come to be the most succesful lineage of heterotrophs, Ossacorpusis (Skeletal Bodies) adapted by developing an internal skeletal structure. These creatures evolved a rigid internal framework, providing greater structural support and enabling more efficient movement. Like analogous species on Earth, such as Haikouichthys and Myllokunmingia, ossacorps likely began with a notochord-like structure, serving as a precursor to more rigid skeletal systems. With this adaptation, ossacorps could grow larger, develop more specialized organs and tissues, and explore new ecological niches. Their internal skeletons would also facilitate a range of locomotion strategies, from crawling and swimming to burrowing and climbing, to eventually walking and flying, one day allowing them to dominate various marine and terrestrial environments.