Welcome miners!

Before beginning with my theory, I wish to clarify that I am neither good at writing nor chemistry, therefore any experts among you will most certainly facepalm more than once. Additionally, you might notice weird punctuation, specifically when it comes to commas, I often use them the way my native language does (which is not English) because the English comma rules, or rather lack thereof confuse me. I welcome any corrections, both in terms of writing as well as those regarding factual inaccuracies. Also please suggest better section headers, I am terribly uncreative. Now without further ado, enjoy the theory!

Introduction

I'm sure we've all wondered, "How do Glyphids sense us?" they don't appear to possess eyes, so could they sense vibrations? It would explain how they can find us through walls, but then how do they know where we are on a zipline? What about echolocation? This would allow them to find us in mid-air but not around objects and how can they not tell the difference between a L.U.R.E. and a player if one of them is just a hologram? Or why do they prefer the L.U.R.E.s over the dwarves? Why do swarmers know where to jump to reach our heads, the most vulnerable part of our body? The information we can gather about Glyphids seems very contradictory when we consider the five sense we are familiar with. So I will make a different claim.

Pheromones

Glyphids can neither sense nor hear us, they don't feel vibrations, nor do they taste us, well maybe after overwhelming you. I believe that their sensing comes down to pheromones. For those unaware, pheromones are chemicals that affect the behaviour of organisms, similar to hormones but transmitted outside the body, and work subconsciously in animals. I do feel obligated to note that dwarves, like humans, are not that good at perceiving pheromones.
We all know a prime display of pheromones in action: Scout's Pheromone Canister. As soon as the bottle cracks, the gasses that get set free cause nearby Glyphids to go haywire, wildly attacking any and all organism around them, regardless whether they're friend or foe. This indicates that there are pheromones that, when applied to a target, make Glyphids attack it. So if said pheromones were applied to, or emitted from dwarves, it would make sense that Glyphids could sense us around obstacles and in mid-air, similar to how mosquitos sense the CO₂ that organisms emit. Or in short: You stink!
It would all be fine and well if that was the answer to everything, but it's not, so we need to go deeper. Cue Nether Portal sounds.

Chemistry

How do these pheromones get to dwarves in the first place? What is their relation to Glyphid-attracting objects like L.U.R.E.s and Dotty? Let's take a detour.
Chemical reactions can be "sped up" (my chemistry teacher made sure to clarify that the reaction itself isn't sped up, but I won't go into detail) by different factors. This is relative to the reaction itself, not all share the same factors. And I'm talking about these factors:
1. Educt concentration
2. Energy influx
Regarding the concentration, if there is a higher concentration, the likelihood of two reagents coming across each other, and therefore a chemical reaction happening, increases with the increase of the educts' concentrations. Of course, you can oversaturate both sides, but if you have a reusable reaction partner, like enzymes, adding the reagent will only yield lesser results once you add more than than what can react in a specific timeframe.
The latter only works with some reactions, or so I believe, but the amount of energy required differs, some reactions only need light to initiate, while others need a couple thousands degrees centigrade.
I will admit, I did not bother researching or thinking about the exact chemical reaction happening here, but here comes the hypothesis I've come up with:
The CO₂ emitted by dwarves reacts with some chemical that's a natural part of the air of Hoxxes IV, creating a substance that works as a pheromones to Glyphids, leading them finding out our precise locations.
Before I continue with that statement, allow me to first offer some alternative ideas for what Glyphids sense I have rejected and why. Ready for a lightning round?

1. Sweat: Wouldn't be sensed in Glacial Strata or through full-body suits and armor
2. Body warmth: Wouldn't be sensed in Magma Core
3. CO₂ itself: Denser than air, would concentrate on the floor and disorient Glyphids as well as prevent them from finding our precise location while in mid-air and prevent swarmers from targeting our heads
4. Ampullae of Lorenzini a.k.a. sensing of electrical currents: Glyphids would be disoriented by Shield Disruption, same with shields and the electrocution status effect.

How does it all happen?

So if CO₂ reacts to a pheromone the Glyphids can perceive, then the increased concentration of CO₂ around our mouth would lead to swarmers being able to accurately pinpoint it. The pheromone particles that were present in the air for some time would gradually drift away from the dwarf, meaning the concentration around the dwarf would be higher than that of the surrounding area, enabling Glyphids to sense both our trails and locations, as well as position from a general area around us, even if yet unexplored.
The reaction would have to be fast for the Glyphids to sense our positions immediately while we're moving and the remaining CO₂ in the air would have to not interfere, hence the concentration factor. The pheromones would also have to have a similar density to air, or be carried by it well enough so that it doesn't immediately sink down when we're on ziplines.
This would explain how Dotty can be sensed... as if her position wasn't obvious enough. But allow me to add the second factor, the energy influx. I believe that the presence of specific wavelengths of light, presumably outside the dwarf-visible spectrum, say UV light, "speeds the reaction up," allowing even the small concentrations of CO₂ in the air to quickly react to massive amounts of pheromones, leading to L.U.R.E.s attracting Glyphids more than dwarves would if they emit UV light. Yet flares therefore don't emit those wavelengths of light, else Glyphids would be attracted to those as well.
This has further implications however. Scout's pheromone canister might actually just contain a lot of CO₂, which would instantly react to lots of pheromones. Furthermore this would prevent Glyphids from inhabiting the surface, as the UV rays of Hoxxes IV's sun would convert the CO₂ into pheromones, disorienting the Glyphids.

Conclusion

You smell, or rather Glyphids smell you. If you stopped breathing, they would stop smelling you, you would die though. All in all, my theory probably has holes or other mistakes, you're welcome to point them out. I hope you enjoyed this read, despite how I worded it all.

Rock and Stone,
Yumikoneko a.k.a. Mystereo

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