“The sandtrout . . .” He fell silent and she wondered why he kept referring to the haploid phase of the planet’s giant sandworm, but she dared not prod him. “The sandtrout,” he repeated, “was introduced here from some other place. This was a wet planet then. They proliferated beyond the capability of existing ecosystems to deal with them. Sandtrout encysted the available free water, made this a desert planet . . . and they did it to survive. In a planet sufficiently dry, they could move to their sandworm phase.”
