Pareidolia is part of the art and culture of radiology. It is the ability or tendency to see faces, animals or objects when given vague stimuli. The classic example is seeing shapes in clouds. It is a subset of the more generic apophenia, which is merely seeing patterns in random data.
Here is a lovely example featuring both a black butterfly and a white butterfly.
Black and white butterflies (ventricles and meningioma)
Being on the look out for such little gems adds an unexpected delight to even the most mundane of studies. We would love you to contribute some examples, and share with us these hidden images.