Ray Stantz claimed to have been present at an undersea, unexplained mass sponge migration. In 1984, Ray used the event as a retort to Peter Venkman; who chided Ray that there was little evidence of the paranormal. According to Peter, the sponges migrated 'about a foot and a half', which led him to believe that it was not as paranormal as Ray thought.
One day in the mid to late 1970s, Ray and two other researchers took a dive in a deep sea submersible vehicle. They witnessed sponges moving literal inches at a time. They tracked and recorded it. After Gozer was defeated, Ray told Rebecca Morales about the migration during his interview but she was more interested in the supernatural.
- In the August 5, 1983 draft, on page 4, Dean Yeager asks Peter if they have seen a ghost yet. Peter tells Dean Yeager and the committee about a rockfall they studied a week ago. Supposedly, stones and pebbles somehow materialized and fell out of the sky from an untraceable source. Peter admits they got to the site right after it happened.
- By the third draft, September 20, 1983, the line is moved to when Peter and Ray trot up the stairs to the library and Ray cites a "multiple high-altitude rockfall" as one psychic occurrence he's seen. Peter tells him he's been hanging out with Egon too much.
- Originally, Ray's line was about a "multiple high-altitude rockfall". Dan Aykroyd had to rerecord the line in a postproduction looping session, where he came up with "mass sponge migration."
- On page 22 of Teenage Mutant Ninja Turtles/Ghostbusters Issue #2, there is a non-cameo reference to Mass Sponge Migration in Ray's locker in an article in the upper left corner.
- In the Dramatis Personae of Ghostbusters International #1, the Mass Sponge Migration is mentioned in Ray's biography. 
- On Cover B of Ghostbusters Year One Issue #2, in the petri dish is a piece of sponge, a nod to Ray's mention of a Mass Sponge Migration at the start of Chapter 3 "Get Her!"
- On page 3 of Ghostbusters Year One Issue #2, Ray recounts the mass sponge migration he witnessed that he mentioned to Peter in Chapter 3: "Get Her!"
- Ray Stantz (2020). IDW Comics- "Ghostbusters Year One Issue #2" (2020) (Comic p.3). Ray Stantz says: "We happened upon a race. Those sponges were really moving, literal inches at a time. We saw it, we recorded it, we tracked it."
- Ray Stantz (2020). IDW Comics- "Ghostbusters Year One Issue #2" (2020) (Comic p.3). Ray Stantz says: "A real honest-to-goodness migration! At no time before or since in the course of history -- as far as we know -- have sponges ever moved so far or so fast!"
- Aykroyd, Dan & Ramis, Harold (1983). Ghostbusters (First Draft August 5, 1983) (Script p. 4). Peter Venkman says: "Stones and pebbles somehow materialize and fall out of the sky from an untraceable source.""
- Aykroyd, Dan & Ramis, Harold (1983). Ghostbusters (Third Draft September 30, 1983) (Script p. 4). Ray Stantz says: "Well, I was at an unexplained multiple high-altitude rockfall once.""
- Shay, Don (November 1985). Making Ghostbusters, p. 25 annotation. New York Zoetrope, New York NY USA, ISBN 0918432685. Paragraph reads: "A similar problem plagued Stantz' "multiple high-altitude rockfall" reference. However, since this bit of dialogue was included in a long shot of the actors, Reitman and his editors were able to rerecord the line and insert it into the soundtrack during a postproduction looping session. Dan Aykroyd came up with his own replacement: "Of course you forget, Peter, I was present at an undersea, unexplained mass sponge migration.""
- Dramatis Personae (2016). IDW Comics- "Ghostbusters International #1" (2016) (Comic Dramatis Personae). Line reads: "Has witnessed an undersea, unexplained mass sponge migration."
- Ray Stantz (1999). Ghostbusters, Chapter 3: "Get Her!" (1984) (DVD ts. 06:52-06:57). Columbia Pictures. Ray Stantz says: "Of course you forget, Peter, I was present at an undersea, unexplained, mass sponge migration."
- Peter Venkman (1999). Ghostbusters, Chapter 3: "Get Her!" (1984) (DVD ts. 06:58-07:02). Columbia Pictures. Peter Venkman says: "Ooh, Ray, those sponges migrated about a foot and a half."