What's That Rock?Ammonite
The coiled shell of an extinct sea animal related to squid and octopus. Ammonites lived from about 400 million to 66 million years ago.
How to identify Ammonite
- Spiral coil with ribs
- Internal chambers visible in cross-section
- Often found in limestone or shale nodules
Often confused with
- Snail fossilsno chambers inside
- Concretions
- Coiled worm tubes
Real or fake?
- Cut and polished ammonites are real, but 'fake' resin copies and painted pieces exist; look at the detail and weight
Is Ammonite valuable?
Common types are inexpensive; rare, large or iridescent (ammolite) specimens cost much more.
Typical retail prices
Collector specimen$8–80each
Typical retail ranges in US dollars, compiled from public dealer and marketplace listings in October 2026. Real prices vary widely with quality, size and origin. This is general information, not an appraisal.
What changes the price
- Preservation: a whole, sharp, symmetrical shell beats a broken or heavily restored one
- Polish and cut: cut-and-polished halves showing chambers or pyrite and opal fills cost more
- Rare types: iridescent ammolite from Alberta and large or unusual species are worth far more
- Authenticity: carved or reassembled pieces are sold as 'natural', check the seams
Uses
- Collecting and display
Care
Fragile. Support pieces and avoid water on pyritized fossils.
Identifying a stone from a description or a photo is an estimate. Many stones look alike. Ask an expert or a gem lab before you buy, sell or rely on an identification.
Updated October 2026