NASA’s Hubble Examines Cloud-9, First of New Type of Object

“We know from theory that most of the mass in the universe is expected to be dark matter, but it’s difficult to detect this dark material because it doesn’t emit light. Cloud-9 gives us a rare look at a dark-matter-dominated cloud.”

The object is called a Reionization-Limited H I Cloud, or "RELHIC.” The term “H I” refers to neutral hydrogen, and “RELHIC” describes a natal hydrogen cloud from the universe’s early days, a fossil leftover that has not formed stars.

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The cloud may eventually form a galaxy in the future, provided it grows more massive — although how that would occur is under speculation. If it were much bigger, say, more than 5 billion times the mass of our Sun, it would have collapsed, formed stars, and become a galaxy that would be no different than any other galaxy we see. If it were much smaller than that, the gas could have been dispersed and ionized and there wouldn't be much left. But it’s in a sweet spot where it could remain as a RELHIC.

https://science.nasa.gov/missions/hubble/nasas-hubble-examines-cloud-9-first-of-new-type-of-object/