bel·em·nite /ˈbɛləmˌnaɪt/
 箭石


 Be·lem·nite n.  Paleon. A conical calcareous fossil, tapering to a point at the lower extremity, with a conical cavity at the other end, where it is ordinarily broken; but when perfect it contains a small chambered cone, called the phragmocone, prolonged, on one side, into a delicate concave blade; the thunderstone. It is the internal shell of a cephalopod related to the sepia, and belonging to an extinct family. The belemnites are found in rocks of the Jurassic and Cretaceous ages. -- Bel*em*nit*ic, a.

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 belemnite
      n : a conical calcareous fossil tapering to a point at one end
          and with a conical cavity at the other end containing
          (when unbroken) a small chambered phragmocone from the
          shell of any of numerous extinct cephalopods of the
          family Belemnitidae