The Progenitor Foundry is the mid section of the Progenitor Mothership and is also the place where the three Hyperspace Cores were constructed. The Hiigaran Fleet Intelligence confirmed that this is also the engineering bay of the Mothership, courtesy of translation of the Oracle.
The Foundry is the most intact part of the Mothership after the ship broke by unknown reason, becoming the Karos Graveyard. It is identified from the other debris by the distinct shape and a large circle at the centre. Three massive pits were located in the centre of the debris, in which the Hyperspace Cores were constructed, although in-game this feature is not seen.