Darkcosmos is an universe made entirely of Dark Matter. It is invisible to normal technology, and anything that is not dark matter that attempts to enter Darkcosmos is immediately turned into dark matter. The only way to observe events inside Darkcosmos is to use a gravitational wave detector from outside of it..... Or not?
there are rumors that there is an infinitely old civilization that has improved the obanium to make a device that allows you to become and manipulate dark matter. This is a device on the Kardashev scale:oblivion
also in this dimension, dark matter may have leaked and got into many universes, as well as our universe. Perhaps even dark matter was the reason for creation our universe .