The phrase "Playing 'Possum" comes from the opossum's way of protecting themselves. Playing possum means to play dead. A 'possum will lay still in hopes an animal will not attack it since it's dead (many animals won't eat prey unless they catch it alive). While playing dead, a possum will secrete really bad smelling fluid from it's anal glands.
EYES
Skull bones protect your brain.
skin
Armadillos will use their claws to defend themselves.
Its exoskeleton.
Eyelids and Eyelashes.
by wings
the head
scales
Your hands! :P
the spinal cord
mad ANSWER: Crossing the arms denotes a person who is shutting themselves off from communication, or a person who is trying to protect themselves (or their ideas).