I think there have been a few instances where they found enough octopi clustered that they were shown to be sociable. This article is about the Octopi cities https://www.smithsonianmag.com/smart-news/octopus-city-obser...

Not that sociable: http://metazoan.net/55-octlantis-media/

> Octlantis is not in any sense a city. It is not a cooperatively built and maintained structure, designed to allow many individuals to live in close quarters. It is an unusually dense collection of individual dens, most of them dug into a bed of scallop shells.