Ectoplasm

From Wiki....

"Ectoplasm (from the Greek ektos, "outside", + plasma, "something formed or molded") is a term coined by Charles Richet to denote a substance or spiritual energy "exteriorized" by physical mediums. Ectoplasm is said to be associated with the formation of ghosts, and hypothesized to be an enabling factor in psychokinesis.

Phenomenon
Ectoplasm is said to be produced by physical mediums when in a trance state. This material is excreted as a gauze-like substance from orifices on the medium's body and spiritual entities are said to drape this substance over their nonphysical body, enabling them to interact in our physical universe."

Physical mediums are rare in modern culture (perhaps because someone might want a sample to test?). Physical medium David Thompson is one of only a few individuals in the world today who claims to produce this phenomenon and has provided photographic evidence of ectoplasm produced under red light conditions. (Ah yes, photographic evidence, perhaps you should look a my post right before this one...)

Although the term is widespread in popular culture, the physical existence of ectoplasm is not accepted by mainstream science. Some tested samples purported to be ectoplasm have been found to be various non-paranormal substances, including chiffon and flakes of human skin.

Other researchers have duplicated, with non-supernatural materials, the photographic effects sometimes said to prove the existence of ectoplasm.

Since its inception in the field of spiritualism, the concept of ectoplasm has escaped to become a staple in popular culture and fictional supernatural lore. Notable examples include Noel Coward's 1941 play Blithe Spirit, and the 1984 film Ghostbusters; in which "ectoplasmic residue" secreted by ghosts is portrayed as viscous, cloudy and greenish-white, similar to nasal mucus, famously referred to in Bill Murray's line, "He slimed me!"