From 2speccers2tools wiki

Overtime, some populations of Nomlights would find themselves within the waterways that are located within Dingus, the relative lack of competition and absence of predators allowed those Nomlights who adapted to freshwater to florish. As they thrived, these freshwater Nomlights gradually diverged from the rest of their species and became something new. This new species would be known as the Deltomlights.

Much like their ancestors, the Deltomlights have a prominent blue photosynthetic pigment within each cell along with some brown pigments though they only assist the blue pigment in getting energy from sunlight. With almost no competition in the Dingus watershed and nothing around to eat them, the Deltomlights have most of the sunlight for themselves. Unlike their ancestors, however, Deltomlights have become colonial in nature, as it meant they can fixed to the riverbed much better than an individual cell so they do not get carried about by the currents. Unlike the Drynom and its descendants, the Deltomlights are highly susceptible to desiccation and so are entirely restricted to aquatic habitats.

Much like their ancestor and relatives, the Deltomlights also aren't diazotrophs, especially since several other lineages of Asshole Cell descendants have monopolized those niches for themselves.