It is the reduce shell in the squid that gives it a somewhat stiff appearance. Within the cephalopods the presence of a visible shell is a major characterisitc that is used to classify them. Probably the body part that is most commonly identified with the cephalopods are the tentacles. The tentacles are powerful arms covered with suction cups. The tentacles are so strong that an octopus can tear apart almost any creature of comparable size.
Cephalopods are so adept at using their tentacles, they can function independently.
However, it is when all the tentacles are functioning together that the true power of these appendages is realized. The other important part of the cephalopods feeding mechanism is its beak. The beak is also very powerful. This is used to crush hard crunchy organisms like crabs and lobsters. One of the features that may not be so well known to most people is that cephalopods in general have excellent vision.