Ammonites

Ammonites are fossilized prehistoric sea animals known as cephalopods with a spiral form similar to a modern day nautilus. The spiral form is clearly evident in some ammonites. In others, portions of a large original fossil have been cut into cabochons and polished. Some areas of the mineral portion of the fossil have been replaced by pyrite so the polish ammonite has a metallic gleam.

Since they can be found in various sizes, ammonites lend themselves to inclusion in jewelry. Ammonites make a terrific focal piece for a necklace or a brooch and are frequently incorporated into jewelry designs. You can see some of my designs that feature ammonites down the left side of this post.

pyritized ammonite in a silver pendant

Ammonites area widely known and common fossils. Ammonites have a typically ribbed spiral-form shell. ’Ammonite’ comes from the Greek god called Ammon (a ram with curved horns).    Ammonites belong to a group of predators known as cephalopods, but they are more closely related to living coleoids such as the octopus, squid, and cuttlefish than to shelled nautiloids like the currently living Nautilus species.Ammonite – fossilized prehistoric sea animals known as cephalopods with a spiral form similar to a modern day nautilus. The spiral form is clearly evident in some ammonites. In others, portions of a large original fossil have been cut into cabochons and polished. Some areas of the mineral portion of the fossil have been replaced by pyrite so the polished ammonite has a metallic gleam.

Ammonites can be found in a wide range of sizes. Specimens have been found ranging from less than a centimeter to 2 meters in diameter. Early ammonites (until the middle Jurassic) were usually less than 9 inches or 23 centimeters. Larger varieties can be found from the upper Jurassic and lower Cretaceous periods.  Female shells of ammonites, like their modern counterpart, the nautilus, tends to be larger than the males. Ammonite shells comprise of individual chambers, each growing in size as the creature grows. Like the nautilus, ammonites retained their original shell throughout their life.

National Geographic is a great resource on these prehistoric creatures. The link is http://animals.nationalgeographic.com/animals/prehistoric/ammonites/