The relatively large and only moon of Alphyth, the Undersea of Moros is an icy, airless world named after the former god of death, Moros. It's size compared to Alphyth makes some scholars call them binary planets, as Moros creates a distinct orbital wobble on Alphyth. In fact, it is this exact tidal heating that gives these distant worlds their survivability- the interior heating that the two produce on each other makes the temperatures underground somewhat livable.

While Moros' surface is airless and inhospitable, it is said to house a sizable subsurface ocean, deep below the ice. As infested with aberrations as Alphyth now, its said that Aboleths stalk the ruins of the undersea settlements in its lightless ocean.

It has had many mining settlements on its surface that have dug deeper into the subsurface ocean.