Definition of "ammonite" []

• The coiled, flat, chambered fossil shell of an extinct cephalopod mollusk that was abundant in the Cretaceous Period. (noun)

American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

• "The closest living relative of the ammonite is the chambered nautilus."
• "There are portraits and the wax seal, made from an ammonite, of the Very Reverend Dr. William Buckland, Dean of Westminster 1784-1856, a geologist who gave the first full description of a dinosaur, but who is better known for his stated ambition to eat a member of every living species of animal."
• "One contained an ammonite, a fossilized nautilus shell."