Talking about the seeds (thank you for this unintentional nudge for an idea) is that maybe UAs are actually seeds, or contain them, for Barnicles? The reason behind this is a theoretical assumption that there is somekind of intelligent life-form behind their manifestation (to me they look to be rather hybrid of biological and artificial elements, very much same as cyborgs or androids). Bear with me, a lot of assumptions and little or none facts, but if the UAs are artifacts of some unknown lifeform, and seems to be connected to the barnicles and meta-alloys as well, this might be some kind of preparation stage, as suggested some previous poster.
UAs somehow create barnacles, or plant their seeds - or something. Barnacles then produce this superior material known as meta-alloys, hints to me that this unknown lifeform is preparing systems where they can harvest important material for something - I think ships, of superior capabilities.
Just a theory, and won't probably hold water in closer examination.
-v
I thought that was what you were alluding to!