Familiar Strangers (Shapes in the Sky)

Tyger! Tyger! burning bright
  In the forests of the night, 
   What immortal hand or eye
  Could frame thy fearful symmetry?
   (William Blake)

What do these portents mean, I've observed them at close quarters once or twice in my life, and what's so uncanny about them is their actual "normality" - they are not like anything we normally witness, yet they kind of appear to be familiar, in some remote sense, perhaps we are very familiar with them from our dreams etc, so maybe this is what explains part of this oddly unique sensation. Yet initially on experencing them there is always a regularity to their geometrical form, which never transgresses at first sighting into the more complicated manifestation of the icosahedron for example, yet with time even this simplicity can appear to change.
The other aspect which is more disconcerting is their total silence while they move above you, and, its not just the absence of engines, but, more revealing it is the total absence of any sound from the wind, which should naturally be produced by any solid body when it obtains the velocity at which these objects move. But, perhaps, this is our very human limitation coming in play here, even though these objects appear to be solid, there is no actual reason why they should be?  The geometry of these objects, usually, a slightly tapering Isosceles triangular form is interesting, as this shape seems to be its normal "at rest state" however, it seems to have the ability to transform itself in a whole combination of other forms (like the Isohedron), depending upon the environment and even the presence of an observer's mind.

I don't know where exactly these creations come from (our minds, the multi-verse, parallel universes, or the frontiers of our very own physical universe, are indeed a combination of them all) but, their innate mathematical form, their seemingly intentional yet also baffling behaviour, would seem to be highly suggestive that we do as a species, share this "physical" and indeed "mental" space upon this planet, with other forms of non-terrestrial intelligences, which seem to be as old as humanity itself.