A cosmic burrow is a wormhole most likely created by (a Cosmic Dominator/a group of Cosmic Dominators) and is inhabited by the cosmic dominators that made it. They're made when cosmic dominators bend space to create 1 way holes in space. The creators of the cosmic burrows then bend space deeper to extend the hole. Most cosmic dominators live in these cosmic burrows, but there are some exceptions for others. Let's take for example Omnius-Realitus, the group of cosmic dominators that created CROM. They live in a hole in Isolation's Reality Tree's trunk.