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Both squid and Cuttlefish I hear.
Cephalopod ink has, as its name suggests, been used in the past as ink; indeed, the Greek name for cuttlefish, and the taxonomic name of a cuttlefish genus, Sepia, is associated with the brown colour of cuttlefish ink (for more information, see Sepia (color)). Modern use of cephalopod ink is generally limited to cooking, where it is used as a food colouring, for example in pasta and sauces. For this purpose it is generally obtainable from fishmongers. The ink is extracted from the ink sacs during preparation of the dead cephalopod, usually squid, and therefore contains no mucus. Recent studies have shown that cephalopod ink is toxic to some cells, including tumor cells. (From Wikipedia)