seriously

I was in the flat looking out of the balcony and behind the building behind our flat was this kind of shifting visual mass, kind of like predator when he is camouflaged - which i first thought was just hot air being ventilated out of one of the buildings, but it wasn't as it was behind the building, and then it just moved off to the right, out of sight, which hot air refracting light wouldn't do either.
it was pretty weird.
probably an ALIEN.
you seen any ufos?