On a day in October 2006, I sat in a dark laboratory at Yale University and zoomed into the fossilized ink of a 200-million-year-old squid relative under an electron microscope. An ocean of translucent balls, each roughly a fifth of a micron in diameter, loomed into view. To the untrained eye, they might have been unimpressive. But I was riveted. These ancient structures looked exactly like the granules of melanin pigment that color the ink of modern squid and octopuses.