Some of the Strangest Things on Earth That Are Only Found in the Deep Ocean

Blue-Ringed Octopus

Although all octopi have their own levels of defense, the blue-ringed octopus is said to be the only one of its kind with a toxin powerful enough to kill an adult human. In 1929, British zoologist Guy Coburn Robson discovered that these creatures turn bright yellow and each ring flashes bright blue for a third of a second after they’ve perceived a threat. In some cases, the rings will flash bluish-green to warn any nearby creature to back off.