The Marshmallow Man is actually the evil god Gozer in disguise. Right as Gozer gives the GhostbustersTM the choice of how he will destroy the world, Ray accidentally thinks about the Marshmallow Man, and at this moment Gozer immediately transforms. To defeat this huge monster, the GhostbustersTM take a huge risk and cross the beams of their proton packs - something you should never do!
Ray is an experienced parapsychologist and has dedicated his whole life to researching supernatural phenomena. Peter and Egon studied with him at Columbia University. He mainly shares his untiring fascination for gadgets and technical equipment with Egon.
The Ecto-goggles are one of Ray Stantz' favorite gadgets: they make invisible ghosts and traces of psychokinetic energy (PKE) visible.