taxon_rank somoholitaceae
Nautiloids are a large and diverse group of marine cephalopods ( Mollusca ) belonging to the subclass Nautiloidea that began in the Late Cambrian and are represented today by the living " Nautilus " and " Allonautilus ". Nautiloids flourished during the early Paleozoic era , where they constituted the main predatory animals , and developed an extraordinary diversity of shell shapes and forms . Some 2 , 500 ___MASK33___ of fossil nautiloids are known , but only a handful of ___MASK33___ survive to the present day . The nautilus ( from the Latin ___MASK60___ of the original Ancient Greek "  ", ' sailor ') is a pelagic marine mollusc of the cephalopod ___MASK70___ Nautilidae , the sole extant ___MASK70___ of the ___MASK89___ Nautilaceae and of its smaller but near equal suborder , Nautilina . Somoholitaceae is one of seventeen superfamilies of the Goniatitina ___MASK99___ . They are an extinct group of ammonoid , which are shelled cephalopods related to squids , belemnites , octopodes , and cuttlefish , and more distantly to the nautiloids . A cephalopod ( pronounced or ) is any member of the molluscan ___MASK50___ Cephalopoda ( Greek plural , " kephalópoda "; " head - feet "). These exclusively marine animals are characterized by bilateral body symmetry , a prominent head , and a set of arms or tentacles ( muscular hydrostats ) modified from the primitive molluscan foot . Fishermen sometimes call them inkfish , referring to their common ability to squirt ink . The study of cephalopods is a ___MASK79___ of malacology known as teuthology . Cuttlebone , also known as cuttlefish bone , is a hard , brittle internal structure ( an internal shell ) found in all members of the ___MASK70___ Sepiidae , commonly known as cuttlefish , a ___MASK70___ within the cephalopods . Goniatitina is one of two suborders included in the ___MASK45___ Goniatitida ; extinct Paleozoic ammonoid cephalopods only distantly related to the Nautiloidea . The octopus ( or ; plural : octopuses , octopodes or octopi ; see below ) is a cephalopod mollusc of the ___MASK45___ Octopoda . It has two eyes and four pairs of arms and , like other cephalopods , it is bilaterally symmetric . It has a beak , with its mouth at the center point of the arms . It has no internal or external skeleton ( although some ___MASK33___ have a vestigial remnant of a shell inside their mantles ), allowing it to squeeze through tight places . Octopuses are among the most intelligent and behaviorally diverse of all invertebrates . Cuttlefish are marine animals of the ___MASK45___ Sepiida . They belong to the ___MASK50___ Cephalopoda , which also includes squid , octopuses , and nautiluses . Cuttlefish have a unique internal shell , the cuttlebone . Despite their name , cuttlefish are not fish but molluscs .