The Black Marble is a yet-unnamed Daemon World. We have no canon name for it and its just called that due to its landscape. During Robot Gullytan's merry pilgrimage to Terra following his resurrection, it was the last planet they encountered during the Maelstrom.
After fighting a few Red Corsairs strongholds, the world was overall...'orderly' for a Daemon World, giving Guilliman some reprieve. The world was of black marble and bloody seas. Nevertheless, the screaming of the bloody ocean was eroding his followers’ sanity, and amongst the ashen skies overhead, huge, dark shapes stirred with the promise of terrible danger. Yet the logistics of stripping the Corsairs’ fortress would take time, even with the Primarch’s Tactical genius.
Guilliman found himself wandering alone through the twisted citadel’s corridors. It was as he entered a chamber of crystal statues that a shimmering mist rose before the Primarch’s eyes. There he caught a willowy figure prancing around the area before speaking...sort of. Whatever it was, Guilliman at least felt that there was no taint of Chaos in this manifestation; the energies given off by the shimmering vision were more akin to those of the Eldar who had aided his resurrection. Whether it was Sylandri Veilwalker, Eldrad or his big titty GF, we have no idea.
But the message the being spoke was a clear direction to get out of that hellhole, so being the rational man he is, Bobby G followed the being's directions and sooner or later, his fleet was out of the Maelstrom...until he got assaulted and captured by the Red Corsair's Blackstone Fortress. Don't worry they got better afterwards.
|The Planets, Systems, Regions and Sectors of the Galaxy|
|Imperial Homeworlds:||Holy Terra - Sacred Mars|
|Primarch Homeworlds:||Baal - Barbarus - Caliban - Chemos - Chogoris - Colchis |
Cthonia - Deliverance - Fenris - Inwit - Medusa - Nostramo
Nocturne - Nuceria - Olympia - Prospero - Macragge
|Notable Imperial Worlds:||Armageddon - Bakka - Cadia - Catachan - Cretacia - Ganymede |
Hydraphur - Necromunda - Phyrr - Pythos - Krieg - Kronus - Sacris
Sanctuary 101 - Scelus - Scintilla - Tanith - Tartarus - Titan - Vigilus
Vraks - Zayth - 108/Beta-Kalapus-9.2
|Daemon Worlds:||Plague Planet - Sortiarius - Sicarus - Medrengard - Glass Moon |
Fleshworld - Bathamor - Black Marble
|Systems and Regions:||Ghoul Stars - Halo Zone - Jericho Reach - Kaurava System |
Solar System - Stygius Sector - T'au Septs - Taelus System - Ultramar
|Types of Worlds:||Agri-World - Craftworld - Daemon World - Death World - Eldar World |
Forge World - Fortress World - Hive World - Civilised World - Tomb World