The tint on those lovely vintage photos you might find in an old family album or on the vintage-look photos taken at amusement parks, actually gets its name from a type of cuttlefish.

The cuttlefish looks nothing like the image that first pops into mind when we hear the word “fish”. It is a type of mollusk that has a porous internal shell, called cuttlebone, and falls into the same scientific classification as the octopus, squid, and chambered nautilus.

Much like a squid, the cuttlefish house ink within their bodies, using it to deceive predators that might attack. If a predator is detected the cuttlefish will shoot its ink into the surrounding water to “muddy” it and confuse the predator, while they jet to safety. Cuttlefish ink is a rich brown, and for centuries their ink sacs were harvested and processed to produce pigment.

Common cuttlefishes are found in the Mediterranean, North, and Baltic Seas. The word ‘sepia’ is the Latinized form of the Greek ‘σηπία’ or ‘sēpía’, (meaning cuttlefish); today’s Italian word for cuttlefish is ‘seppia’.

Sepia ink was commonly used to write with in Greco-Roman civilizations, and is known to have been used as early as Ancient Rome. It became a particularly popular paint pigment for artists in the 18th and 19th centuries.

When sepia toning for photography was invented in the early 19th century, its name came from the distinctive hue of the sea creatures' ink, although it’s not known if the ink itself was used in the photo process.

More Info: en.wikipedia.org