Thumper
A stake driven into the sand to drum up a rhythm that lures sandworms to the surface.
Drive this small mechanical stake into a dune and set it thumping. The rhythm mimics movement across the sand closely enough to pull a nearby sandworm up from below. Fremen riders plant thumpers on purpose when they mean to summon and mount a worm. They time the device and their own approach with a precision that only comes from a lifetime spent reading the desert, so Shai-Hulud never catches them flat-footed. The same trick doubles as a decoy. Set one at a distance and a worm's attention drifts away from a group, or from equipment that needs protecting. The device itself could not be simpler. Using it well cannot be faked, and a miscalculated approach to open sand kills fast.
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