An octopus reportedly using projectile weapons

I can't actually see the shells being thrown in the video.

Those ornery octopuses have also taken to hurling objects at each other, like shells and bits of seaweed, blasting them through the water with high pressure. And while Godfrey-Smith says there may be other explanations for this behavior, the number of direct hits has him suspecting that the octopuses are using projectile weapons.

"It would be quite significant if it's happening," says Godfrey-Smith, who has been collaborating on this research with David Scheel of Alaska Pacific University. "In general, projectile use is pretty rare among animals."

He says they've got a lot more observing to do before coming to firm conclusions about the shell-chuckers. In the meantime, he refuses to be baited by sensationalizing reporters. "The prospects for octopus takeover are still fairly remote at present," he says.

https://www.npr.org/2015/08/30/436085657/watch-octopuses-appear-to-take-up-arms-as-submarine-warfare-escalates