I was just talking about this very subject with a friend yesturday!
We were discussing the way that Poltergiests appear as stereotypical images (monks, small children etc).
I read a fantastic book some years ago (but stupidly lent to someone who never returned it

), full of various experiences from priests involved in exorcisms. One particular chapter dealt with the subject of spirits and demons appearing to the priests in different shapes and forms. One priest saw a hideous octopuss-like creature, but another who was with him during the exorcism saw a huge spider..........
Hammy x x x