There exists a parallel universe next to ours called the warp, in which inhabit creatures called angels or daemons. These creatures don't exist as physical entities, but abstract manifestations based on human emotions. Fear, hate, anger, joy, love, etc, are all represented by these creatures, and are the embodiment of these human emotions. Whenever a daemon or angel crosses into our world through gaps in our reality, they take on physical forms that are somehow linked to these emotions as well as the myths that surround them. These forms are meant to cause the highest amount of anxiety based on that feeling in humans. A daemon based on power and rage may take the form of a dragon, et cetera.
These entities can't die permanently, and instead fade into nothing after sustaining heavy damage, there essence fading back into the warp. However, daemons can be captured and held prisoner for long-term use. Scientologists are the ones which study these entities to find out how they work and how best to defeat them. One curious discovery that was made is that these entities have a functioning biological structure. organs, blood, bones, and everything else that goes with a internal structure can be found.
These creatures are meant to be manifestations of our deppest emotions, so it would make sense that their physical forms would be ones that cause those deepest reactions in us. What doesn't make sense is that they would have any internal biology at all. They have no real need for it, since they dont depend on it to survive. They can sustain heavy damage and simply reform themselves multiple times due to their warp energies, so there seems to be no logical reasoning behind having an internal structure modeled off of biological life.
What would be the reason for this?