Fear of anger (or of expressing one's anger): This is a creature who has the potential to be dangerous (claws, teeth, quills), but is intentionally restraining itself (claws are scratched dull, wears a muzzle, etc.)

Fear of making decisions: choices lead to action, so the main part of this creature (containing all the vital organs) has become a static, almost plant-like shape.  Its multiple appendages serve as proxies that allow it to experience the result of different choices without the dread of missing out by "choosing wrong."

Fear of insanity:  This creature's fixation on the state of its mind has become such an obsession that it focuses on nothing else.  Its gaze is turned inward so outward senses are diminished: eyes have developed cataracts, muscles have atrophied (I want to redesign this and make its legs more spindly).  It has placed its brain in a place where it feels it can be protected.

In the spirit of delving into the the biological classification of these creatures, I am interested in the possibility of showing some of their skeletal structures.  This is "fear of chins":

I've also created a clay mockup of "fear of failure."  Unfortunately I discovered too late that my camera has disappeared, but I will bring the object to class.