SOCCER-SIZED CRYTAL-LIKE SPIKED BALL, Easily Missed If One Is Not Looking Directly At It.

Soccer-ball-sized craft that I could see thru much like a dandelion flower seeds just before you blow them.  It was made like a lot of spikes in two heights, though, and if I had not been looking in that exact spot at that exact time, I would never have seen it.  It was outside the window that overlooks the space between our building and the next, a width of about 5 feet betweein the two buildings.  The day was overcast but it was light outside.
 No country, or group of countries could have made this object.  I heard it make no sound but, then, it was outside the window, and it appears to use the air as a stepping stone and it glided toward the window as I happened to look that direction.  It stopped, pivoted once, paused, pivoted again, and left quickly in the direction from which it came.
 The best way I can describe seeing it is like seeing Predator, wherein one can look directly at it and not see it unless it moves.  And if you are looking a few feet to the side of it, one would not see it probably.  It was too small to have occupants since it was about 10 to 12 inches in diameter and a portion of that diameter seemed to be made of spikes, but you can see thru it.  It moved "with purpose", though, and could not have been some eye phenomenon because I saw it pivot twice.
 I only saw it once, and have never heard of anyone quite describe what I saw, or at least I do not know of anyone whose description matches mine.  I did see a fairly similar depiction of my craft, but is was all black in the book, and there was no additional informaton.  I think a good description of the basic shape is that of certain pollen when viewed with an electron microscope, but that would be shape only.  The color is like a crystal that reflects the colors of the overcast sky at daytime.
 It did not emit lights or beams, left no trail, and did not land or make any sound.  There were no lights on the object, no aura or haze around it.  It did not change colors any more than a series of crystals would.  There was no aircraft in its vicinity, and it had no noticeable affect on any equipment in my livingroom where I was when I saw it.  I do not have pictures of it.
 My sense is that it was a probe of some sort, gathering information of some sort, and it may have taken a picture perhaps on the first pivot.  Who knows?  It is just a guess...
Witness indicates that the date of the incident is approximate.  PD