Original sentence: Although the practice of psychic surgery varies by region and practitioner, there are some themes which are common to the practice.Some psychic surgeons will then hold up objects,  which they say are human tissue removed from the patient's body
Edited sentence: Although the practice of psychic surgery varies by region and practitioner, there are some tropes common to the practice.Some psychic surgeons will then hold up objects, such as animal organs, which they say are human tissue removed from the patient's body