Original caption: Ammonite fossil. Ammonites are extinct marine invertebrates. They first appeared in the Late Silurian to Early Devonian period (around 400 million years ago) and became extinct at the end of the Cretaceous period (65 million years ago). --- Image by © Gavin Kingcome/Science Photo Library/Corbis
Schnecke No. nautilus_cut_11496.tif
Nautilus shell. Close-up of a sectioned shell of a nautilus (Nautilus pompilius), showing the spiral structure and chambers of mother-of-pearl (nacreous). The nautilus is a marine cephalopod related to the squid, which inhabits the Indo- Pacific region.
26 Jan 2012 --- Sea shell, X-ray. This sea shell is from a marine gastropod mollusc (sea snail), with the mollusc living in the space inside the shell. The shell mainly comprises calcium carbonate, which is embedded on an organic scaffold. This shell is formed from secretions produced by the mollusc, and grows in size over time, following a spiral pattern. The X-ray shows internal details of this pattern. --- Image by © Gustoimages Ltd/Science Photo Library/Corbis
26 Jan 2012 --- Snail shell, X-ray. This shell is from a gastropod mollusc (snail), with the mollusc living in the space inside the shell. The shell mainly comprises calcium carbonate, which is embedded on an organic scaffold. This shell is formed from secretions produced by the mollusc, and grows in size over time, following a spiral pattern. The X-ray shows internal details of this pattern. --- Image by © Gustoimages Ltd/Science Photo Library/Corbis
Schnecke No. nautilus_cut_11517.tif
Nautilus shell. Close-up artwork of a sectioned shell of a nautilus (Nautilus pompilius), showing the spiral structure and chambers of mother-of-pearl (nacreous). The nautilus is a marine cephalopod related to the squid, which inhabits the Indo- Pacific region.
Schnecke No. nautilus_cu11518.tif
Nautilus shell. Close-up artwork of a sectioned shell of a nautilus (Nautilus pompilius), showing the spiral structure and chambers of mother-of-pearl (nacreous). The nautilus is a marine cephalopod related to the squid, which inhabits the Indo- Pacific region.
26 Jan 2012 --- Sea shell, X-ray. This sea shell is from a marine gastropod mollusc (sea snail), with the mollusc living in the space inside the shell. The shell mainly comprises calcium carbonate, which is embedded on an organic scaffold. This shell is formed from secretions produced by the mollusc, and grows in size over time, following a spiral pattern. The X-ray shows internal details of this pattern. --- Image by © Gustoimages Ltd/Science Photo Library/Corbis
10 Oct 1997 --- Ammonite. Fossilised spiral shell of an ammonite, an extinct squid-like cephalopod animal (sub- class: Ammonoidea) related to the living nautilus. The outer ridges of the shell are seen. Internally the shell was divided into chambers; by pumping water into and out of the chambers the animal could move down and up in the water. This sea creature lived in the outer chamber of the shell. Many species of ammonite flourished from the Devonian period (400 million years ago) until becoming extinct at about the same time as the dinosaurs at the end of the Cretaceous period (about 65 million years ago). This specimen was found in the Sahara desert, once a sea. --- Image by © MARTIN BOND/Science Photo Library/Corbis