The BBC has captured incredible underwater footage of an octopus collecting the halves of a coconut shell in Indonesia to use as protection at a later date. 

In the clip, a flounder is following the veined octopus (Amphioctopus marginatus) as it scuttles to find the second half of a coconut shell. Although the video seems to suggest the flounder is about to stir up trouble, it is more likely trailing the octopus for a very different reason. 

“The flounder is definitely not a predator of the octopus,” said Dr. Jennifer Mather, a professor at the University of Lethbridge who studies octopus cognition, to IFLScience. “But fish often follow octopuses out hunting. The octopus is going to ‘scare up’ escaping small animals that the flounder can catch.”

The octopus is a soft-bodied creature that is vulnerable to many predators, including fish and marine mammals. And out on the open seafloor, there is often no place to hide, so this octopus is carrying the coconut shells around as protection. 

"Tool use per se doesn’t indicate intelligence, there are some fairly automatic manipulations that fit the definition," said Mather. "But what does show intelligence is the planning that octopuses use, and the variety of situations they adapt to. So the octopus that carried around the coconut shell must have anticipated that it would need it later, dug it out of the sand and carried it around until it was ready to rest.”

The footage is part of Life Story, a BBC One series shot by their Natural History Unit in Ultra High Definition (4k).