and last for today: tile answers needed!

i need ideas for what to do about this:

somehow, while i was storing my school boxes in the dining room, a piece of blue construction paper must have fallen out right under the skylight, and then gotten covered up by more boxes.  at any rate, it transfer printed to my saltillo/terra cotta tile floor:

that's a better isolated image of it.  i need to figure out what to use to get it off.  actually, it seems a bit fainter now than it did a few days ago when i first revealed it; since it's right under the skylight, will the same force that transferred it there eventually  make it disappear, you think?--you know how fugitive blue is, which is how it got there in the first place.  i don't want pristine tiles-- they're saltillo, after all and when i first put them in i even was hoping for the stray chicken footprint/goat hoof, but no-- and i usually relish whatever marks happen, but this purple blotch is just too...