Cuttlefish. A cephalopod related to the squid. The flesh of the cuttlefish is meatier and has a more complex flavour. Both the cuttlefish and the squid have an ink sac. The liquid it contains can be used in the cooking process but it should be added towards the end or it will coagulate. The ink of the cuttlefish is generally felt to be richer, denser, smoother than that of the squid. It more commonly means grey mullet (US: striped mullet).