The Milky Way, the galaxy we live in, is one of hundreds of billions of galaxies strewn across the universe. Their variety is stunning: spirals, ring galaxies shaped like star-studded loops, and ancient galaxies that outshine virtually everything else in the universe. But despite their differences, and the mind-boggling distances between them, scientists have noticed that some galaxies move together in odd and often unexplained patterns, as if they are connected by a vast unseen force. Galaxies within a few million light years of each other can gravitationally affect each other in predictable ways, but scientists have observed mysterious patterns between distant galaxies that transcend those local interactions. These discoveries hint at the enigmatic influence of so-called "large-scale structures" which, as the name suggests, are the biggest known objects in the universe. These dim structures are made of hydrogen gas and dark matter and take the form of filaments, sheets, and knots