The term was to described the substance which comes from the body of a psychic medium during a seance. It has been variously described as being a gelantinous, jelly-like and viscous, and is usually white in color, and characteristically comes from the medium's mouth.
Spiritualists believe it to be the materialization of the astral body.
Some mediums have reported they experienced pain when the ectoplasm was touched or exposed to light. Other samples of ectoplasm have been proven to be fabrications when their composition was determined to have been egg-white, cheesecloth or wood pulp.