In 2015 and 2016, researchers observed and filmed instances in which gloomy octopuses (Octopus tetricus) in Jervis Bay, Australia threw debris around themselves and sometimes at other octopuses.

This was the first time such throwing behavior has been observed in octopuses.

What was going on? Were these intelligent creatures merely rough-housing or having a pillow fight?

Led by Peter Godfrey-Smith at the University of Sydney, the researchers analyzed 24 hours of footage and identified 102 instances of such behavior amongst a group of about 10 octopuses.