In History of Man and the tapes of 1952, Ron discusses the thetan living in "spirals", going through stages of being a "young" and then an "old" thetan and then dying and then beginning a new spiral. This usage of "spiral" came from the idea that the thetan was on a declining spiral and each of these young to old periods represented one turn around the spiral.
These turns around the spiral appear to be the lifespan of a theta body which the thetan has his energy, machinery, pictures, etc. wrapped up in. To the best that I can determine, there are a number of layers of these things and they to some degree mimic the later series of universes that we have come through. In metaphysics they also have some idea of levels of spiritual bodies with the astral body being the lowest.
Of special significance is the "energy" or "theta" body which goes back to what I refer to as the "thought" or "theta" universe which is 3 universes back. This is where the person thought that he was an energy production unit and this theta body is a simple cloud or sphere characterized by having an energy level and an energy production capability. At that time, the thetan believed himself to be one of the "thought" people in conflict with the meat body people who were breaking out of the conflicts universe and invading. This body type has much of his identity and also his energy production capability tied up with it. And because it is in agreement with energy, it slowly decays (grows old).
But it was not actually a pure energy body because energy (at least on the later track) requires particles in motion. The actual structure was more like a cloud of golden specs constantly dancing around, and as it ages, these specs slow down and eventually collapse into a condensed point of mass. The thetan's idea when this happens is that he is dead and it ends up as some sort of theta gravesite, usually out in deep space somewhere or at the bottom of a trap. Of course its boring being dead, so he projects out a bit of himself which picks up another theta body, but deep down, he still thinks he's dead and just dreaming about a new life until the new one gets so distracting that he forgets about being dead. But even with this, only his awareness has moved on, he still leaves part of himself and a good bit of his stuff behind in the dead theta body.
Now most of this is pretty speculative, and there's lots of work yet to be done on the subject of processing these theta bodies, but I have found one thing that I am quite confident of, and which is extremely beneficial and workable. And that is to find these points of spiral death and blow entities and split pieces of yourself out of those locations.
And that is actually a good technique for any level of dead body including the
meat body. Blowing BTs out of the grave in France where I was buried last lifetime significantly opened up my recall
of that lifetime