We now also know that their ink is astonishingly long-lasting -- as in 95 millions years long. Case in point is this illustration depicting a prehistoric octopus, drawn with ink taken from the same fossilized cephalopod, aged 95 million years old.
According to This Is Colossal, the drawing was done by Norway-based Dutch artist Esther van Hulsen, who was given the ancient ink by paleontologist Jørn Hurum. The ink itself was taken from a fossil discovered in Lebanon in 2009; according to the museum's acquisitions page, it's an eight-armed species of extinct octopus called Keuppia, which lived during the Cretaceous age.
The ancient ink is still surprisingly vibrant after being reconstituted with water, despite the passage of time. It's also significant as this dark substance was essential to the creature's existence. “Knowing that this animal has used this ink to survive is absolutely amazing,” says van Hulsen.
Funnily enough, this kind of special artwork drawn in fossilized ink has been done before -- by nineteenth-century self-taught English paleotologist and fossil collector Mary Anning, whose groundbreaking discoveries helped to shape scientific thought at the time. Anning found the first complete Plesiosaurus skeleton, one of many finds in a fascinating life story that deserves to be told on its own. For the modern iteration, you can see both the drawing and the old ink over at the Natural History Museum in Oslo; you can also visit Esther van Hulsen.