Professor E. Gadd's Research Journal

Professor E. Gadd's Research Journal is a series of stories written in journal format on the official website for the Nintendo 3DS version of Luigi's Mansion. In it, Professor E. Gadd relates the accidental discovery of a green slimy, "Goo," responsible for the creation of Gooigi.

XXX-001 An Accidental Discovery
E. Gadd begins by making a short introduction on a "strange liquid energy" collected from ghosts he had befriended. He posits that said energy is "the key to many, many new inventions," but admits that he initially struggled to uncover its uses. His failed experiments with the energy included poking it with iron, pouring it on rubber, and even absent-mindedly dipping a donut into it.

The professor recounts that later during his research, he was startled by a Hider ghost that had escaped from its confinement, causing him to spill the coffee he was drinking into a vial containing ghost energy. He claims that the coffee, described as a "Lunoman Greenie blend from Evershade Valley," quickly reacted with the energy inside the vial, leading to the creation of a green viscous substance. E. Gadd recognized the substance as a new chemical element and called it "Goo," which he then assigned the "00" entry in the.

XXX-002 Characteristics of "Goo"
E. Gadd writes that he wishes to discover the real-life uses of "Goo", and decides to perform various expirements on it. He first tested fire on the Goo. The substance was melted, revealing a weakness to fire. The professor followed up by spraying water on the Goo, which yielded the same result. However, E. Gadd notes that the bits of Goo which did not touch the water had moved away from the hazard.

The professor also tells that he has discovered other unusual properties of Goo. He reveals that Goo will push back when touched, as well as react to sounds such as music. E. Gadd concludes that Goo is able to react to outside stimulation, and writes that he believes there is a greater purpose for this new element.