It was given this planetological classification in no small part thanks to Manuxet's Human population being scattered across thousands of islands that make up the endless archipelagos spread over the planet's surface.
Though fairly distant from its system's star, Manuxet has a temperate environment due to high levels of insulating gases in the upper atmosphere. The relatively small amounts of land surface and its three moons combine to trigger frequent and severe storms that often accompany the unpredictable tidal cycles.
The rich sea life has provided a reliable source of food for its Human settlers through the dark millennia of isolation, which enabled them to survive and thrive down through the ages.
When the Achilus Crusade made Imperial contact with the world again, it found a population that had suffered a severe technological regression. The natives lived a nomadic lifestyle, typically following the seasonal migratory patterns of some of the sea's enormous schools of fish.
Their religion had drifted away from the Imperial Cult, and was instead focused on appeasements to gods of the sea and sky. Imperial technology was initially heralded as magic, which missionaries of the Ecclesiarchy used to aid in conversion efforts.
This mission went reasonably well, and Imperial Compliance was achieved within a span of six solar months. After that time, refineries were established to process the bounty of Manuxet's oceans.
Over the ten Terran years since Compliance was achieved, an estimated 40% of the world's sea life has been processed and shipped off-planet to feed the soldiers of the Achilus Crusade.
The Adeptus Munitorum insists that the oceans are being reseeded with additional life so that the planet may maintain its newfound status as an Agri-world, but the current consumption rate vastly exceeds the rate of aquaculture growth.
While the Imperial forces feast on this system's bounty, the natives have been forced to change their lifestyle. The schools of fish that they once followed have been depleted. Though they are not starving, the foods they eat are new and unfamiliar to their palates. Their gods have been replaced.
New habitats have been built that protect them from the forces of nature, but which trap them in sterile buildings away from the natural environment in which their culture had flourished for many standard millennia.
At the same time as these changes were implemented, the Imperium was forced to withdraw troops to deal with the Tyranid threat. In their absence, the natives have grown increasingly restless.
Numerous incidents have occurred where members of the population have abandoned their Imperial responsibilities and attempted to return to their nomadic lifestyle. Priests of the Ecclesiarchy have filed reports of heresy, as natives return to their primitive religions.
Worse yet, there has been an increase in the numbers of missing persons reported among members of the Imperial government stationed on Manuxet. Some reports indicate that these Loyalists have been swayed and gone native. Others are gruesome tales of hideous murders over petty matters.
Interspersed with these reports are sightings of man-sized creatures with exoskeletons and claws creeping through the civilised regions under the cover of darkness.
- Deathwatch: The Achilus Assault (RPG), pp. 59-60