Among the four categories of beings in the first era, the ones that are most irregular are the Amara, in our tongue: Undying.
They started to form in the lands below as death became more and more common. The Amara are simple to understand. In the areas of the lands below, there are sections where the concentration of dark substance is more dense, so, when a beast dies, their soul wander in search of stability as souls are made of only the most unstable and fleeting substances that there are. Therefore they go to the lands below where the most stable substance - Dark - is more prominent. But, not all places in the land below hold the same density of dark substance, therefore the souls of the beasts tend to wander and gather in the same place.
After a while, this concentration of souls in the same place started to trap other souls that ended up wandering to the same place, the density of souls in one single spot started to cause a curious phenomena and the souls started to become one. As the process continued and the huge souls were starting to form, at some point the collective of those souls started to slowly become one single hum and the many experiences of those short lived souls started to create a self consciousness and a mind has emerged from many of those super souls.
Thus the Amara were formed, and since their main substance is dark, they quickly formed bodies, but their bodies were most curious, the many Amara that there are are completely different and each one is a perfectly independent and unique creature, their bodies are a amalgamation of many beast parts, reflecting the many beast souls that once resided within. So diverse are the Amara that they dont have a single aspect to share.
They do not die, as they were never alive. they never fade, as the dark element dont allow much change even with the passing of the ages. And they live forever, owners of knowledge and wisdom unparalleled by any. With each passing day, they grow stronger and wiser, until the end of the times.