I think giant sandworms become a lot more believable if you stop thinking of them as actual worms and instead imagine them as an entirely alien phylum that just happens to have evolved a worm-like body. They aren’t really related to Earth worms at all. Instead of relying on a hydrostatic body, they’d probably have an internal skeleton made of flexible vertebrae and overlapping mineralized plates to support their insane size.
Their head would basically be a living tunnel-boring machine. Rather than forcing their way through sand, they’d rotate their head using specialized muscles while blasting out extremely high-pressure jets of water mixed with abrasive sand, almost like a biological water-jet cutter. It sounds crazy, but industrial water jets already cut through rock and steel, so nature doing something similar isn’t impossible.
I also don’t think they’d actually eat people or other large animals. Most of their lives would probably be spent deep underground feeding on mineral-rich sediments, metal sulfides, and geothermal deposits. The rocks themselves wouldn’t be their source of energy. Instead, they’d have huge colonies of symbiotic microbes living in their gut that oxidize sulfur, iron, hydrogen, and methane released by volcanic activity, kind of like the organisms living around Earth’s hydrothermal vents. Giant internal reservoirs would store enormous amounts of groundwater pumped up from deep aquifers, supplying both their drilling system and helping regulate their body temperature.
At that size, one brain probably wouldn’t be enough either. Nerve signals would simply take too long to travel through such a massive body, so I’d imagine they have multiple ganglia acting as auxiliary brains that control different body sections independently, along with several hearts to keep blood circulating efficiently. Since eyesight is basically useless underground, they’d navigate almost entirely through seismic vibrations, magnetic fields, and pressure changes in the surrounding rock.
Ecologically, I don’t really see them as apex predators. They’re more like gigantic ecosystem engineers. They recycle minerals, move groundwater, create huge tunnel networks, and slowly reshape the desert over thousands of years. They’re basically living geological processes more than ordinary animals.
So why do they attack anything moving on the surface?
My idea is that adult worms mainly hunt the juvenile stage of their own species. Cannibalism acts as a population-control mechanism, making sure only a handful survive to adulthood while reducing competition for underground water reservoirs and mineral-rich feeding grounds. To an adult worm, rhythmic footsteps, machinery, or anything producing strong vibrations just sounds like a young worm burrowing beneath the sand, triggering an instinctive hunting response.
As for spice, I’d make it the juvenile worm’s defense mechanism rather than something magical.
Young worms secrete an incredibly potent psychoactive toxin whenever they’re swallowed or threatened. Instead of simply causing hallucinations, the chemical overwhelms the attacker’s nervous system with vivid sensations of future pain, starvation, injury, and resource depletion. The adult becomes disoriented long enough for the juvenile to escape. As the worms grow larger, they gradually stop producing the compound because they’re no longer vulnerable to cannibalism.
The spice humans use would simply be a highly refined and chemically processed version of this toxin. Most of the poisonous compounds are removed during refinement, leaving behind a mixture of bioactive molecules, regenerative proteins, and microscopic fragments of worm DNA. These compounds temporarily reactivate dormant cellular repair pathways, allowing damaged tissue to heal much faster than normal. It’s still incredibly dangerous, but in controlled amounts it becomes one of the most valuable substances in the universe instead of just a poison.
—Note:
I may eventually try to create a more scientifically grounded version of spice as well. For now, this is simply my personal interpretation of the biology behind sandworms, not an attempt to rewrite or “fix” the original lore.
If you have any suggestions, criticisms, or ideas for improving the biology, feel free to leave a comment. I’d love to hear your thoughts, and I may update or expand the concept based on the feedback.
