
While it's not made entirely clear why they end up sharing the same hallucination - although the couple in the beginning also appeared to be sharing one - Mulder and Scully eventually come to realize what actually happened, and that they're being slowly digested underground by the enormous fungus monster. Scully later goes to find to Mulder, only to also be exposed. As often happens, Mulder and Scully split up, which turns out to be a mistake, as Mulder is exposed to the hallucinogenic spores released by the underground creature. It's arguably one of The X-Files' darkest moments apart from the infamous episode "Home," and sets the stage for what's to come when Mulder and Scully are sent to investigate what caused the two mysterious deaths. The couple lies down together in bed, only for the scene to then cut to their skeletons lying together in a similar fashion. Two hikers head home after what seems like a fun day outdoors, but signs appear that something is off. "Field Trip" begins with a rather ghastly setup. When examined more closely though, there's reason to believe that the pair of X-Files agents never actually made it out of the creature's lair. At least that's what appears to happen at the end of the episode.

Of course, Mulder and Scully, prove to be the ones finally capable of breaking the "Field Trip" creature's spell and living to fight another day. Related: X-Files Theory: Cigarette-Smoking Man Has John Doggett Captive How exactly it's able to tailor these hallucinations to specific victims, or exactly how intelligent the giant fungus was, goes unanswered by the episode's end - but it's hardly the weirdest X-Files monster, not with "death fetishist" Donnie Pfaster in the mix.

The creature's hallucination states were very intricate, and could seemingly make the victim perceive anything the creature deemed necessary to placate them into staying asleep.

Once in that state, the malevolent organism trapped its prey underground and placed them in a kind of narcosis, slowly digesting them. The X-Files monster-of-the-week fungus was massive, spreading for miles underground, and was able to release spores that caused its victims to enter a hallucinogenic state.
