ammonoid

• Nom désignant les coquilles fossiles spiralées et cloisonnées de mollusques marins éteints, souvent trouvées dans les roches sédimentaires, ainsi que les animaux eux-mêmes. Ce sont des céphalopodes fossiles caractéristiques de l'ère secondaire.

A noun referring to one of the coiled, chambered fossil shells of extinct marine mollusks, often found in sedimentary rock.

1. Extinct marine molluskC1formalscientific

   An extinct group of marine mollusks with a coiled, chambered shell, related to modern squid and octopuses.

   Ammonite (mollusque fossile)

   • The fossil collector found a perfectly preserved ammonoid in the limestone quarry.
   • Ammonoids are important index fossils for dating rock layers.
   • The spiral shape of the ammonoid shell is a classic example of logarithmic growth.

   Synonymesammonite