Let me begin by saying that I have been writing a grimoire of spirits that identify themselves as “sea demons.” One such spirit is called Karigel, who takes the form of a crocodile.
In one ritual with Karigel, I underwent deliberate possession. As our consciousnesses merged, I felt myself unable to stand. I had to crouch in a position natural to a crocodile. My arms felt clawlike, and stocky. I became aware of a tail extending behind me.
Now, I had a camera on me, so I know i did not physically become a crocodile, but my astral self, my psychology, my physical perception, and my physical movements all shifted to go in line with the spirit that was taking over me.