Looks like an iPhone 52
Just a simple screen, just three buttons... Apple's remote control for the universe?
None of the buttons seems to be red, so the "nuke the galaxy" option seems to be missing.
Well, "where" is possibly Terra's system, with beautiful Saturn drifting by -- although there must be many gas giants with rings, galaxy-wide.
"What" is a bit harder. We have no scale for this doodad. It could be a handheld remote - or it could be a ship piloted by Steve/Skitter's people. Whatever it is, though, we can assume it is drifting and not being piloted at present.
I shall now retire to quiver in muted anticipation...
i'm surprised no one's suggested 'hitchhiker's guide to the galaxy' yet. i mean, sure, the words on the cover have rubbed off due to time and use, but that's just to be expected.
To me, that square on the front looks like a screen.
I think it might be a message carrying device of some kind.
Or a piece of the Spark of Thought.
Or maybe it has the mind of that robot thing that the outcast Maker guy from before meade.
....or maybe that's what the Makers really want the humans to "RETURN"?
...Seems dubious, but I can't eliminate the possibility without hearing something that indicates otherwise.
I found another occurence:
It seems it's on all sorts of continuum stuff (including the top of the staff of the commander of the Spark of Thought) And it's been around for a while.
I'm going with my Message Capsule theory.
Spark of Thought: "A probe has discovered a planet with ring ships. Jump there?"
It is "the spirit" (probably of the robot maker) given to the pre-maker that had been alive only 14 hours by the Maker that created the "abomination" - a spirit that created (the robot maker). It was probably lost sometime after the ship piloted by the pre-maker encountered the ore that shot through the pre-maker's skull and the singularity ring and has been following the path of the ship at a slightly slower pace to earth for all these centuries, now about to finally arrive and "be free".
I think that to the makers' way of thinking, the robot maker is the spirit (they seem to say "spirit" where we would say "created object"). (Hence, a spirit that is also a maker is a serious problem; hence, the plot.)
I totally buy that the floating object is whatever the young maker was carrying when he fled, though. It's either that, or the Doctor's phone, which explains why he never answers.