Most people get cold feet or the jitters if you mention these creatures to them. I would agree theorems are scary things! But what do they look like?
Well here is what I've been able to come up with so far:
Theorems: (The main species of mathematica theoria) This creature can generally be found standing on hilltops throwing large boulders at passersby. Sometimes also referred to as golems or basilisks.
Lemmas: (Subspecies mathematica lemmia) These small furry creatures can often be found scuttling down the corridors of your local mathematics department. They come in yellow, green and a kind of purply colour. Often seen throwing themselves off rooftops in large groups.
Propositions: (Subspecies mathematica minutae) These tiny creatures are surprisingly agile and get very aggressive when cornered, beware! They are quite difficult to trap and quite often suffer from the left-up-to-the-reader syndrome.
Corollaries: (Subspecies mathematica corolloria) These creatures are generally blue-eyed with sweet smiles and very sharp teeth which cut through flesh like straight razors. They are four legged, hairless and quite ubiquitous.
Postulates: (Subspecies mathematica postularia) These creatures resemble a cross between a rock hyrax and a bush pig. They can often be found hanging on to bushes in arid semi-desert climates whistling to eachother.
If you have any additions please feel free to /msg me.