If you're a fan of ghosts and spirits -- not to mention the Ghostbusters franchise -- you've heard of ectoplasm. According to the true believers, this ghostly goop is the physical residue of entities from beyond the mortal plane, summoned by mediums to communicate directly with the living. But what exactly is this stuff? How does it work? In tonight's episode, Ben, Matt and Noel dive into the strange history of this ethereal substance, separating fact from fiction in a quest to finally determine the truth about ectoplasm.