Hahaa! Nobody guessed it (but darn, did you folks have some pretty sweet ideas), it's charcoal! It's there because Kokko sneezed really hard once. No, that was a lie, actually she farted.
And what's this?, another crowdfunding campaign to make the print run for a webcomic is about to end in the next couple of days? So here's a quick heads up for anyone who would like to grab a book. The comic is called The End (it's in the middle of a character origin short story right now) and here's a link to the Kickstarter page. Aww, no hardcover option...doesn't matter, I still want it! And you guys go take a look too, okay? It's pretty neat.