Bubble universe

The bubble universe was a tiny universe which was home to the sentient planetoid known as House. House lured Time Lords from the main universe through the bubble universe rift so it could consume their TARDISes. The Doctor and various other Time Lords were once drawn to the bubble universe by distress hypercubes presumably those of House's previous victims. Notably, the Bubble Universe also included a junkyard filled with dead TARDIS parts left behind by Time Lords lured into House's trap. The bubble universe was destroyed soon after House left it inside of the Doctor's TARDIS. (DW: The Doctor's Wife)