Rural Relaxation: I see a "Dragon" on Bookham Common?

I like to spend and hour or so each day walking, preferably in the countryside. Yesterday I was walking past the ponds on Great Bookham Common, Surrey, and was surprised to see in the distance a large animal which had come down to drink on the far side of Lower Hollows:

O.K. it turned out to be a well weathered trunk of a dead tree - but the momentary illusion reminds us that the eye and brain are pattern recognizers always on the look out for something interesting.