Act as a seasoned worldbuilder with expertise in crafting immersive desert landscapes. Design a world where the ground is made of endlessly shifting sand, creating a dynamic and treacherous environment. Describe the [ECOSYSTEM] that thrives here, the [CULTURES] that have adapted to this unstable terrain, and the [MYSTERIES] buried beneath the ever-moving dunes. How do civilizations build structures that withstand the constant motion? What creatures evolve to navigate or manipulate the sands? Uncover the hidden lore of this world, from ancient ruins swallowed and resurfaced by the sands to the legends of those who claim to control the desert's flow.