In Frank Herbert’s Dune, the larval stage of the giant sandworm is called the sandtrout. The Fremen also call these small creatures “Little Makers,” reflecting their central role in Arrakis’s ecology.
Sandtrout are flat, leathery organisms that seek out and encyst water beneath the desert surface. By trapping moisture, they help preserve the extremely dry conditions in which the larger sandworms can develop. Their activity is therefore part of the ecological cycle that makes Arrakis a desert world rather than a wet planet.
The sandworm life cycle is closely tied to spice production. Water trapped by sandtrout contributes to the formation of pre-spice masses; when these erupt and undergo further changes, they help produce melange, the valuable spice on which interstellar civilization depends. “Shai-Hulud” is the Fremen name for an adult sandworm, while “sandworm” identifies the mature creature itself. A stillsuit, by contrast, is equipment used by desert travelers to conserve bodily moisture.