This was kind of a dare, really.
The Pebble is a triangular stone of unknown type that is about three inches in length, and most notable for two things. The first is the white line that scores one-third of the Pebble. The second is the way that moving the Pebble leaves behind a white line of force in the air that seems to be functionally equivalent to a monomolecular blade. Worse, the line persists for at least a day before it finally fades. Or, possibly, the universe heals the wound being made in it.
Needless to say, it’s a bad idea to touch the line. It’s also probably a bad idea to try to use the Pebble to make simple shapes (and thus presumably make holes in reality). ‘Mostly’ because nobody’s had the madness needed to try. Shoot, the last person to even suggest the possibility got shot in the head as a safety precaution.
And after that particular applied exercise in interpersonal relationship breakdowns, the Pebble went on to kill fifteen other people (purely by accident) before the investigators at time simply gave up, dropped the damned thing in a swimming pool, and filled the pool with concrete. That was forty years ago; most of the people involved in the original operation are dead by now, but it’s still probably going to be years yet before the Pebble’s an active danger again.
Probably.
Oh, you’re taking dares now?
(whistles innocently)