Cuttlefish

Cuttlefish, or cuttles, are marine molluscs of the suborder Sepiina. They belong to the class Cephalopoda which also includes squid, octopuses, and nautiluses. Cuttlefish have a unique internal shell, the cuttlebone, which is used for control of buoyancy. Cuttlefish have large, W-shaped pupils, eight arms, and two tentacles furnished with denticulated suckers, with which they secure their prey. They generally range in size from 15 to 25 cm , with the largest species, the giant cuttlefish (Sepia apama), reaching 50 cm (20 in) in mantle length and over 10.5 kg (23 lb) in mass.

Source: Wikipedia