They are the largest known gravitationally bound structures in the universe and were believed to be the largest known structures in the universe until the 1980s, when superclusters were discovered.
Son as estruturas máis grandes unidas gravitatoriamente do Universo e ata a década de 1980 críase tamén que eran as estruturas máis grandes do Universo, ata que se descubriron os supercúmulos.