The Mother Nest could be used to describe in general terms the group consciousness of the Conjoiners, or specifically the Conjoiner "homeworld".
At twenty kilometres in diameter the asteroid that served as the functional center of Conjoiner society was big, but there were at least a million bigger orbiting Epsilon Eridani. A transparent film of plastic—undetectable to Demarchist sensors—was built on its exterior, giving it a structural integrity it naturally lacked. When first selected as their new base of operation, Conjoiner rockets were attached and fired to stabilize its spin, while eighty per cent of its interior was hollowed out and its newly-reinforced inner shell was lined with cryo-arithmetic engines.
Once completed the internal space was fifteen kilometres in diameter, and consisted of five layers. The four outer layers spun to simulate gravity in half-gee increments, while the center -- a three kilometre wide sphere -- was an area of no gravity, housing greenery, micro-habitats, and frequented by the elderly and children. Concealed entry shafts allowed moderately sized vessels access to the asteroid's docking berths and repair bays.