I've got a wiki I've been working on for my own open source project, complete with descriptions of aliens of my own quirky design.
I thought you might find them useful, as I'm perfectly willing to share them. They're under the Creative Commons Attribution-ShareAlike 3.0 License, but if you need another license, I'm willing to be flexible. I seem to remember you guys want all parts of the project under the GPL, even the non-software parts, right?
You'll find a list of the aliens I've designed at:
http://deimosproject.wiki.sourceforge.net/Alien+RacesOf those I believe the Molluskos and the Teachers would make excellent XVI fodder, perhaps with a bit of tweaking. Unfortunately, I've no pictures, as my talents lie in writing rather than drawing.
The Molluskos should work fine as is, especially the Soldier caste.
The Teachers should also work if you either tone down or omit the bit about their immune system. I could see an interesting sub-plot with the Teachers being freed of their XVI infection if desired; perhaps XVI is simply the one disease they could never conquer and a war is constantly being fought for control of their bodies. They'd most likely be used in some kind of research/scientific role, because in essence, they have a genetics/medical lab built into their bodies. Alternatively, you could just use their body form and most of the anatomical info from the wiki, omitting what you don't like.
Combat-wise, the Molluskos soldiers would be a pain; bullets should bounce right off their shells (or do very little damage) and they could hide inside them between the player's turns. I'd assume this would be what happens when they "crouch". Salt would be the deadliest thing you could use against them. Snails do tend to die rather quickly when exposed to it...
Teachers on the other hand would be fairly weak against bullets, but could be easily "genetically customized" for almost any task. You could do something similar to humans having cybernetic implants. Players would have to be cautious with them as they could have almost any unusual ability and could easily take on traits of the other aliens by sampling their DNA.
