In this video, a veined octopus, Amphioctopus marginatus, demonstrates its ability to use a tool for defense. The octopus carries a coconut shell as it travels, then, when danger approaches, it tucks itself inside for safety. Clever!
Finn, J.K., T. Tregenza and M.D. Norman. (2009) Defensive tool use in a coconut-carrying octopus, Current Biology, Volume 19, Issue 23, R1069-R1070, 15 December 2009