
Threads form and decay naturally.
Here I'm defining magic as preventing the natural decay of threads.
It's assigning excess meaning to something that has a little bit of meaning.
Like you know that sandwich you ate for breakfast? Ordinarily, you probably don't care that you ate a turkey, but what if the meaning/emphasis on the dead turkey was exaggerated disproportionately? Perhaps the next time you walk by a flock of birds, pigeons will poop on your head.
As for the random rock, it would really only work if someone spent a long time curating and taking care of all the threads associated with the rock, because otherwise they decay to meaninglessness over time naturally. So it must be an awfully special rock!