I mocked up a super simple thing like this in HTML5/JS here.



It is the simplest it could possibly be just every pixel an even chance of being foreground or background and mirrored.
There's a wierd bug in Firefox where every sprite is identical (RNG seems to be getting reset or not reseeding, if I stick an alert in between tiles they do generate nicely, wierd. ), but it works fine in Chrome (apart from the ubiquitous blur).
Refresh to regenerate. If you've got chrome hit the image button to get an image to save.

I've spent quite a bit of time playing with RIST over the years.  I think your may produce better results, though of course the "evolve" button was fun.

I have to agree with Argyle; the elements mesh surprisingly well, and I really like the sense of brightness they give overall.

Some fossil rpg enemies (vaguely ff6-styled/inspired.)  I like how the dinosaur turned out (though I know that anyone who knows the first thing about therapsid anatomy would probably be deeply offended), but the other two (trilobite and giant/cyclops skeleton) feel iffy.

(note that the skull of the cyclops is inspired by a dwarf mammoth skull, which may have been a root of cyclops/giant myths.)

Just out of curiosity, is there something I'm missing about the sponges?  they seem kind of out of place in a book/ink-themed zone, and they don't really fit visually either; compared with your other elements, they look kind of rough and unfinished.  The bindings on the books also look a bit unusual.  They're quite thick, and seem to extend over the pages.
I actually kinda like the look of the sea of ink as you have it now.  It's definitely worth experimenting with larger waves, but these do a pretty good job of conveying the look simply and effectively.
One thing that might be fun (or you might already be doing) would be to have bookends occasionally appear in the walls.  That could add a bit of texture and diversity as well.
Anyway, crits aside, I really do like the way this is going.

@Froli:  I actually have a sonic tablet, though it's an offbrand.  I got it for free for testing through my dad's work.  Let me just say that they must have substantially improved the technology since then if Wacom is willing to make one, because the one I have is pretty bad (draw circle; get oval) despite the cool concept.