Squid produce a special type of ink known as sepia ink. This ink is made up of melanin pigment, which is also present in human skin. When the squid releases this ink, it clouds the water around it, making it difficult for predators to see the squid. Sepia ink can also be used as a natural dye in art and can produce a variety of earth-tone colors, including sepia brown and black. The ink can be extracted from the squid and used in calligraphy, painting, and writing, though most modern-day artists and writers use synthetic sepia ink rather than squid-produced ink.