Although Cyanopluma were the first animals to abandon a sedentary lifestyle and become motile. Life would remain slow for some time and with few evolutionary pressures life appeared to meet a stand still; However, as cyanopluma became better adapted to their environment their digestive systems became more efficient consequentially allowing them to consume more food and grow larger faster, gradually this resulted in a surplus of cyanopluma and a more competitive environment. Some cyanopluma adapted to this new competition by consuming smaller members of their same species. One might think cannibalism would be the last thing to kickoff the diversity of life; despite this, that is exactly what it did, predatory cyanopluma had to become more specialized to keep up with their smaller more agile prey resulting in the formation of an entirely new group of life.
Protomalaconatatoria or proto-squims would be the first free swimming nekton of Aether's oceans, descending from cyanopluma; They have achieved this feat by adapting the roof of their mouths along with the first pair of rhinophores into 3 sided jaws, the remaining two pairs of rhinophores would go on to develop into sensory appendages with one pair remaining external acting as barbells and the other internalizing to become a more specialized nare. They have adapted the foot of their ancestors into two segments, two pelvic fins used to control direction and two lateral undulating fins used to propel themselves forward. The six simple eyespots of their ancestors have become more developed allowing the formation of simple images. Like their ancestors their bodies lack skeletons and so they remain small never growing larger than a few inches in length. These adaptations were all made to facilitate a slightly carnivorous diet; In other words, greater maneuverability allows proto-squims to better capture small cyanopluma, Pliaceps, plankton, and algae. These adaptations also help smaller individuals to escape the prevalent cannibalistic tendencies of even larger cyanopluma.
A single proto-squim gently hovers in thick murky green water.
Though the proto-squims were the most successful free swimming creatures of their time, they were quickly surpassed as they had many inefficient attributes leading them to be quickly outcompeted as generations of more competitive squims were selected for. Yet with the death of the proto-squims came the birth of the true squims; These adaptable squims developed novel characteristics completely unique to any other cyanopluma descendant. Unlike any of their relatives the squims were able to internalize their gill skirt reducing drag and making them less vulnerable. However from this innovation arises a new problem, in order for gas transfer to occur water must constantly flow over the gills, they also must maintain a large surface area and avoid being compressed. The undulating lateral fin constantly flushes the gills with water solving the first issue, to prevent the gills from being compressed a special cartilaginous scaffold developed, which will be referred to as "gill rings". From these gill rings the squims would go on to be the first animals of Aether to develop internal skeleton giving them access to niches other groups of animals could only dream of.
A true squim brushes against the xelp, several others are seen in the distance.
True squims became a diverse clade of animal, with their streamlined bodies and adaptable maw's the squims could develop into a wide variety of niches. Like their ancestral form some remained largely generalist, while others adapted more predatory behaviors, a commonality among all diets was the exaptation of what was originally the secondary rhinophore as a portion of their lower jaw, becoming more apposable while less powerful compared to the other segments. Alterations of the the traditional bauplan were plentiful, some became long and slender, some nearly lost their pectoral fins, others flattened and became ray-like. These attributes lead the squims to colonize each corner of Aether's oceans, inhabiting xelp forests, tropical regions, the arctic and even abyssal depths.
Despite appearing very different to earth fish, squims would take on niches similar to them, and would go on to be the most agile creatures to roam Aether's oceans quickly radiating into a diversity of niches from small scavengers to graceful herbivores, and even fierce predators.