Nellai is a galaxy located in the Degelio subgroup, in the distant reaches of Florathel Cluster. It's not really clear what kind of galaxy this one is, but what is certain is that it's evolving between two types. The galaxy is considered a transition galaxy, the only known example in the local cosmos. It is evolving from an irregular galaxy to an elliptical galaxy, which is marked by the depletion of the last gas and dust reserves in the galaxy to form the last generation of massive stars the galaxy will likely see, which are forming at this present moment.
The galaxy is home to several nations, most of which are dying due to the scarcity of important resources and the relatively low metallicity, as well as conflicts within the galaxy. Therefore it can be said that the galaxy is dying, both in its starforming capability and life.
Nellai was relatively complex in structure, however its transition into an elliptical is erasing a lot of that structure.
The core is the densest part of the galaxy. It houses the central cluster, located inside the most violent starforming region in the galaxy, which isn't actually that violent by most standards. At the center of this cluster is a supermassive black hole with a mass of about 440,000 solar masses. Surrounding this starforming region are huge areas of stars densely packed together, and stellar mergers are relatively common, and so this environment is relatively hostile to life.
The middle regions in Nellai are what makes it similar to ellipticals, and these types of regions are found everywhere in ellipticals. These regions are composed of relatively old, low-mass stars, with very little gas and no star formation. The old stars give these regions a yellow tint, but in Nellai, that is balanced by the blue light from the starforming regions. Life in Nellai is most prevalent in these areas.
The starforming regions are regions of ionized gas surrounding massive hot stars, where all the young stars are located. These regions are what keep Nellai from being a regular old elliptical galaxy, as they are not found in those and only in irregular galaxies. However, the galaxy’s supplies of gas are small and due to run out in about 100 million years, and so the regions are some of the last which will exist inside the galaxy. Life is not very common in these areas because the stars are too young to have developed life, and also because of the radiation pouring from the massive stars and occasional supernovae.
The halo is the most diffuse part of the galaxy and the furthest from the centre. It’s not really considered to be inside the galaxy and is just a collection of stars with tens to hundreds of light years between them. The halo contains the very oldest stars in the galaxy and is home to many RR Lyrae variables, which were used early on to find the distance to this galaxy from others and the galaxy’s size. Life is very rare here because there are basically no stars to host it.
Nellai formed after most galaxies in the local cosmos, about 12.3 billion years ago, from the remaining gases that the Degelio Galaxy wasn’t able to accrete. In the millions of years that followed, the galaxy was a violent place, where star formation was rampant and supernovae periodically destroyed any possibility of life in the blob of a galaxy.
After a few hundred million years of violent star formation, Nellai settled down into a relatively large irregular galaxy, forming stars at a regular pace. Life was rare in the early galaxy, although there were small instances of life here and there, each event separated by a few hundred million years. The aeternum event had little effect on the galaxy, even if all life had been wiped out.