The fugitives used genetic technology to revive key figures from Dune's past-including Paul Muad'Dib and Lady Jessica-to use their special talents to meet the challenges thrown at them. Before, though, there's no evidence they existed as giants.At the end of Frank Herbert's final novel, Chapterhouse: Dune, a ship carrying a crew of refugees escapes into the uncharted galaxy, fleeing from a terrifying, mysterious Enemy. This is a common occurrence when animals encounter a habitat they can thrive in. Once they had an entire planet to roam, it's easy to see them growing to gigantic proportions. Even if it was identical, the worms could have been much smaller, making their spice production negligible. We're not certain what the sandtrout's adult phase was like before reaching Dune. They might have died out on their own home world, or maybe some large lump of rock floating in asteroid belt WAS their home.

If this is the case, Arrakis is the only planet they managed to survive on. The precursor to sandtrout could have ridden inside of an asteroid to reach Dune. There are theories that life on Earth originated elsewhere, deposited here by a crashing comet or some similar collision. This doesn't mean there are aliens in the Dune universe. Since the Dune universe is a future extension of our own, Leto II could be referring to our prehistoric times, making it doubtful that humans brought them to Arrakis. I can't help but hang my awareness on the word 'prehistoric'. Presumably this was when the sandtrout were introduced, since a transformation this grand would take thousands of years to occur. Just above that quote, Frank Herbert mentions that in prehistoric times water was abundant on Dune. I just don't see how humans could have known of the existence of sandtrout and not the existence of spice. unless the sandtrout can some how spread to other planets on their own. Who the heck brought the sandtrout to Dune?. In a desert environment with large sandworms, I would say the spice would have definitely had to have been produced even on the sandtrout's homeworld. I think it is fair to say that pre-god emperor sandtrout only existed in environments that allowed for the maturation of sandtrouts into adult sandworms. And adult Sandworms require large expanses of desert to survive. This seems highly unlikely to me seeing that adult sandworms are a clear part of sandtrout life cycle.

Or the sandtrout was known but didn't produce spice on their original planet. So who brought the sandtrout to Dune originally? It had to be an alien race or some hidden branch of humans. LetoII doesn't specify if the Fremen brought them during their exodus but it is clear humans didn't discover spice until they came to Dune. ''The sandtrout', he repeated, 'was introduced here from some other place''(Children of Dune). But, this particular sentence caught my attention. Early in Children of Dune, LetoII reveals to Ghanima that the ecological change Dune is experiencing will lead to the death of all sandworms.

Dune sandworm