Physical Description of a Kra'vak

Am I being especially dense, or did I miss a physical description of
the Kra'vak somewhere? I have all the GZG books, but I don't remember
seeing a description of what a Kra'vak looks like (the creature, not a
ship). I don't have More Thrust with me right now as a friend is
looking through it, but is there a description in there? 

I vaguely remember a description but I need something more concrete.

Allan Goodall	     agoodall@sympatico.ca

"Once again, the half time score, 
 Alien Overlords: 142,000. Scotland: zip."
  - This Hour Has 22 Minutes