English: Chandra's image reveals a complex of several multimillion degree Celsius gas clouds in the process of merging to form a massive galaxy cluster. A few of the point-like sources in the image are associated with galaxies in the cluster, but the rest are probably distant background galaxies, many of which contain active supermassive black holes. The bright gas cloud on the upper left is the core of the cluster and envelops hundreds of galaxies. The large cloud on the lower right envelops hundreds of galaxies and has a much lower concentration of iron atoms than the core. It is thought that this cloud has not been enriched by the stripping of iron-rich gas from its member galaxies because it has yet to fall into the core cluster. Observations of Abell 2125 provide a rare glimpse into the early steps in the process of building one of the most massive objects in the universe.