I was reading our Metaphysical Biology article and came across this line.
"Angels are made of a substance known as as Particle wave matter or PWM which can hold its shape even without a soul"
This puts it into my head that this implies several traits of the Angels that are never directly stated, but are no less implied in the series.
So we know that an Angel with no soul can hold form and that makes it the vessel to become an Evangelion.
But this brings to mind the Angels that are killed.
In Rebuild they explode into an LCL like substance, which raises a few questions by itself since PWM is supposed to be capable of existing without a soul, but maybe we can just count that as the Evas destroying the Angel's AT Field, I dunno.
But the major thought that struck me came from the original series, where we see several Angel corpses that then have to be cut up and removed, which led me to a theory.
Now we know the Angels are immortal pretty much from their description and capable of regenerating from injuries to everything but their core. But when they die their "soul" having left their bodies, by the very nature of PWM, does this mean that Angels do not decompose?
Ramiel had blood from what we saw, but got cut up into squares and hauled away, but what do you do with a massive alien creature that in theory, should not decompose naturally?
Are dead Angels recycled as parts for Evas? Do they sling up bits of them to use as Eva target practice? What did they do with Shamshel and Ramiel, the Angels they salvaged?
It's not a world shaking question, but it is an interesting thought. By every indication, unless explicitly destroyed by the Evas, the Angels are eternal. Hell, what's left of Gaghiel should be at the bottom of the Ocean, and Sandalphon is in the middle of a Volcano.