Cephalopods, marine mollusks - octopus, cuttlefish and squid, are among the largest, strongest, fastest, most cunning, and ferocious of all animals, but many of them are quite harmless.
In many countries cephalopods are valued as food. The internal shell of the cuttlefish, the cuttlebone, is used in bird cages - they are a source of lime salts. Sepia ink a rich brown pigment used by artists, is made from the fluid ('ink') these animals discharge as protection. Never very popular in the U.S. except in ethnic communities (Greek, Italian, Asian, Portuguese).
The Greeks hurl them against rocks and the Portuguese beat them with bottles to tenderize them before they are cooked. When properly prepared they are as delicate and tender as chicken.