dark galaxy

The term dark galaxy is used for the concept of an object like a galaxy except with no stars, essentially a dark matter halo with some gas (hydrogen) clouds and/or dust. Such an object should be detectable through gravitational lensing. Some would use the term even for such an object with stars if they produce no observable EMR. Theories have been developed regarding their origins and characteristics. Some objects are proposed as candidates (one was the Smith Cloud, some of the others being candidates for almost dark galaxies), but likely some discussion remains both regarding the nomenclature and whether the candidates qualify. Though it seems an exotic concept, it seems plausible to me that if dark matter exists, there could be cases where a region of its high density has not (yet) produced stars.