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Ammonites

Coiled shells of extinct marine molluscs, the classic British fossil.

Devonian to Cretaceous; most British specimens are Jurassic. · Beginner to find

Engraved illustration of a coiled ammonite shell showing ribbing and the inner whorls

What is it?

Ammonites were shelled cephalopods — relatives of today's squid, octopus and nautilus — that lived in the seas from the Devonian until they disappeared at the end of the Cretaceous. Their coiled, chambered shells fossilise readily in marine mudstones and limestones, which is why they are so common along the Jurassic coastlines of Dorset, Yorkshire and Somerset.

What does it look like?

A flat spiral, usually a few centimetres across but occasionally much larger. The surface often carries fine ribs running from the centre outwards, and a broken specimen shows internal chambers divided by wavy walls.

How to identify it

  1. 01Look for a spiral that tightens evenly towards the centre — a snail (gastropod) spirals into a cone instead.
  2. 02Ribs usually run across the whorl from the inside outwards, sometimes branching.
  3. 03Split nodules and loose beach pebbles often hold whole specimens; check the flat faces of freshly broken rock.
  4. 04Iridescent or golden specimens are usually preserved in pyrite and need careful storage as they can degrade in damp air.

Where to find ammonites in the UK

Map of the United Kingdom showing fossil hunting regionsLyme Regis — DorsetCharmouth — DorsetSeatown — DorsetEype Beach — DorsetKimmeridge Bay — DorsetRingstead Bay — DorsetChurch Ope Cove, Portland — DorsetKilve Beach — SomersetWatchet — SomersetFolkestone Warren — KentHunstanton — NorfolkWhitby — North YorkshireRunswick Bay — North YorkshireRobin Hood's Bay — North YorkshireStaithes — North YorkshirePort Mulgrave — North YorkshireSaltburn-by-the-Sea — Redcar and ClevelandDunraven Bay, Southerndown — Vale of GlamorganLlantwit Major — Vale of GlamorganPenarth — Vale of Glamorgan
  1. 01Lyme RegisDorset · DorsetAmmonites · Belemnites · Bivalves · Marine reptile remainsBeginnerFamily friendlyBeach, CliffExplore location →
  2. 02CharmouthDorset · DorsetAmmonites · Belemnites · Bivalves · Fossilised woodBeginnerFamily friendlyBeach, CliffExplore location →
  3. 03SeatownDorset · DorsetAmmonites · Belemnites · Bivalves · Fossilised woodEasyFamily friendlyBeach, CliffExplore location →
  4. 04Eype BeachDorset · DorsetAmmonites · Belemnites · BivalvesEasyFamily friendlyBeach, CliffExplore location →
  5. 05Kimmeridge BayDorset · DorsetAmmonites · Bivalves · Fossilised wood · Marine reptile remainsModerateFamily friendlyBeach, Cliff, Geological siteExplore location →
  6. 06Ringstead BayDorset · DorsetAmmonites · Bivalves · Sea urchins · GastropodsModerateBeach, CliffExplore location →
  7. 07Church Ope Cove, PortlandDorset · DorsetBivalves · Gastropods · Ammonites · Fossilised woodModerateBeach, CliffExplore location →
  8. 08Kilve BeachSomerset · SomersetAmmonites · Belemnites · Bivalves · Marine reptile remainsModerateFamily friendlyBeach, Geological siteExplore location →

Regions

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