Greetings! As some may know, I had the distinct honor of being "the third guy" through a period of Aquaria's development. And inside this period was another period where we were all physically working together in LA. Ah, the memories... Classic times!
This gives me a chance again to thank Alec and Derek for playing such a big role in getting me back into game development. (THANKS, GUYS! I'll love you forever.)
Anyway, this "wurm" is indeed a lost form of the final boss! It was going to be the third form, if I remember correctly. I was working on it personally. But getting the movement right was tricky for a number of reasons (not least of which being my own incompetence), so it wasn't quite done by the time we all returned to our respective homes. Some time after that I had a pretty nice mental collapse (don't worry, I'm fine now) and, long story short, the Wurm Form got cut from the final game.
But hey, look what I found on an old memory key -- maybe the only Aquaria development screen I took:
Ignore all the crazy dev stuff. 
As you can see, the wurm would swim around the area, curving and twisting about, doing little loops and stuff, all the while its nasty faces shooting at poor Naija. There was going to be other stuff too, but now my memory's getting fuzzy. (I think you had to hurt each face separately?) Oh, and you could ride on its back, which was pretty cool. I
think (Alec may correct me on this) Naija being able to grab onto objects was originally added for this boss. If there's ever a Directors Cut of Aquaria, I'd love to give him another go. It'd probably take me like a day now, oy.
While I'm here, if anyone's interested (ha!), here's my work setup at AQ HQ (it's pretty hardcore):
It was a man sandwich, Derek on my left, Alec on my right.Also we played M. Dickie's
classic Hard Time a bit:
Figure out how you feel about that.Okay, starting to get misty, I should go.
