nautiloid
Spiral-shelled cephalopod
A nautiloid is any member of a group of cephalopod mollusks characterized by external shells, typically coiled or straight.
The chambered nautilus is the best-known living example, but nautiloids were far more diverse in ancient seas—their fossil shells appear in rocks dating back nearly 500 million years.
The term also works as an adjective describing nautilus-like features: nautiloid shells, nautiloid fossils.
Flexible grasping appendages
- siphonLiquid transfer tube
- mantleCovering or wrap
- beakHorny avian mouthpart
- molluskSoft-bodied invertebrate, often shelled
jet propulsion · predator · invertebrate · soft-bodied · radula · hunting · camouflage · squid
Preserved ancient organism
- ammoniteExtinct spiral-shelled cephalopod
- OrdovicianPaleozoic geological period
- SilurianPaleozoic period, mid-range
- DevonianGeologic period, 419-359 million years ago
Cambrian · Paleozoic · extinct · petrified · stratigraphy · sediment · fossilization · excavation
Having enclosed compartments
- septumInternal anatomical partition
- buoyancyFluid's upward resistance
- gas-filledContaining trapped vapor
- nacreousResembling pearl's iridescence
calcified · coiled · whorl · suture · mother-of-pearl · ornamentation · aperture · hydrostatic
Curve maintaining constant tangent angle
- coiledArranged in spirals
- whorlSpiral arrangement of ridges
- golden ratioPhi, roughly 1.618
- FibonacciPisan mathematician, numeral importer
tentacles
Flexible grasping appendages
mollusk · jet propulsion · predator · invertebrate · soft-bodied · radula · hunting · camouflage · squid · octopus
fossil
Preserved ancient organism
- ammoniteExtinct spiral-shelled cephalopod
- OrdovicianPaleozoic geological period
- SilurianPaleozoic period, mid-range
Devonian · Cambrian · Paleozoic · extinct · petrified · stratigraphy · sediment · fossilization · excavation · specimen
chambered
Having enclosed compartments
- septumInternal anatomical partition
- buoyancyFluid's upward resistance
- gas-filledContaining trapped vapor
nacreous · calcified · coiled · whorl · suture · mother-of-pearl · ornamentation · aperture · hydrostatic · floatation
logarithmic spiral
Curve maintaining constant tangent angle
- coiledArranged in spirals
- whorlSpiral arrangement of ridges
- golden ratioPhi, roughly 1.618
ocean
Massive saltwater body
Indo-Pacific · reef · tropical · marine · saltwater · depths · habitat · nocturnal · scavenger · migration