Octopolis and Octlantis are two non-human settlements occupied by gloomy octopuses (Octopus tetricus) in Jervis Bay, on the south coast of New South Wales.
Octopolis consists of a bed of shells (mainly scallop shells) in an ellipse shape, 2–3 meters diameter on its longer axis, with a single piece of anthropogenic detritus, believed to be scrap metal, within the site.
Octopuses build dens by burrowing into the shell bed.
The shells appear to provide a much better building material for the octopuses than the fine sediment around the site.
In 2016, a second settlement was found nearby, named "Octlantis," which includes no human-made objects and can house similar numbers of octopuses.