There's a bit of confusion what kind of race the Niscassar really are. 
Fan Art has decpicted them as squid creatures, like the mindflayers/Illithids from DnD or the star spawn of Lovecraft.
However, when asked what the Niscassar are, Jervis Johnson, a (former) designer at Gamesworkshop stated, that they are 
indeed "flat polar bears". Yes, really. It's not clear if that answer was a joke.
Since there is no "true" official statement in the scource books or the black library novels, so it's kinda up for the players 
to decide what the Niscassar look like. 
So, I decided to go with the polar bear appearance in this pack, even it's kind of ridiculous. I included some squid art aswell, namely character & races portraits


If you want them to look fully like squids, I suggest you use the Wekkarus ui Blackstorck has made for his 
"Beyond Extended Universe" and "Alien immersion" mods. You can find them here:

http://www.matrixgames.com/forums/tm.asp?m=3657646
http://www.matrixgames.com/forums/tm.asp?m=3651979

