The Mu Capricorni system holds four Arean-type worlds, only one of which has been terraformed; the others are AreanLacustric or AreanTundral subtypes
A rocky terrestrial class planet, the Arean Type (also known as Type R) is usually of fairly small mass, uninhabitable, and marked by vast expanses of open rock land or sands. Wind is the dominant weathering mechanism. Geological activity varies, but the older the world, the less active it is. Atmospheres tend to thin the younger they are. If there is a large moon, these worlds tend to remain geologically active throughout their history, due to tidal flexing. If near or within the life-zone, Arean worlds are comparatively easy to terraform, and for that reason are much in demand by interstellar development corporations.
Perhaps the most common of the Terrestrial Group, these are worlds whose carbon cycle has long since broken down due to the cessation of geological activity. The planetary atmospheres and magnetic fields are typically quite sparse as a result, and the surface often retains features first laid down during the planetary formation period. These worlds may also experience geological upswings, either due to some outside influence, or a build up of internal heat over the eons. During these periods, the planet may be habitable, but this will likely last only for a few ten to hundreds of millions of years.