Huge Large Quasar Group. Source
Scientists have found something quite staggering. They believe that they have found a group of quasars that spans 4 billion light years and has the mass of 3,000 trillion suns which is about the mass of 1.3 million galaxies. That mass is mind boggling. Like, seriously. It's huge.
Because of its size it has been unofficially dubbed the Huge-Large Quasar Group. The picture shown here gives you some idea of scale. This large group of quasars is millions upon millions of light years away, but it still manages to span 15 - 20 whole degrees in the night sky (for reference, the celestial sphere is 360 degrees). That's amazing.
This discovery challenges the assumption that the universe is more or less uniform from all vantage points. If such a large structure actually exists, it is likely that the cosmic microwave background would be measured differently from different locations, that mass is not evenly distributed, and that the universe isn't evenly expanding in all directions.
I recommend reading more about this. There are several informative articles, I will provide links below.