unlit matter is a mysterious substance composing most of the fabric universe,now widely thought to be some form of massive exotic particle. An intriguing alternative view is that unlit matter is made of black holes formed during the first moment of our universe's existence, known as primordial black holes. Now a scientist at NASA's Goddard Space Flight middle in Greenbelt, or Maryland,suggests that this interpretation aligns with our knowledge of cosmic infrared and X-ray background glows and may explain the unexpectedly high masses of merging black holes detected last year.
Source: phys.org