What stones to look for on a fossil beach

• Anything grey and flat that splits into layers — open it and look at the fresh face
• Rounded, heavy, slightly rusty lumps — ironstone nodules, which often hold ammonites
• Black, very light pieces on the Yorkshire coast — likely jet
• Golden, metallic-looking fragments — pyritised fossils, common at Charmouth and on Sheppey
• Glossy dark triangles in the fine shingle — shark teeth

Concentric rings in a pebble are usually just weathering, not an ammonite. Tube-like holes in chalk or wood are often borings made by modern shellfish. Black shiny fragments on southern beaches are frequently coal or sea-worn glass rather than jet — coal gives a black streak, jet a brown one.

Dendrites, the black fern-like patterns sometimes seen on limestone, look convincingly like plant fossils but are mineral growths along a crack.

Wet it and look again. Feel the weight. Look for symmetry and repetition. If a broken surface shows radiating crystals, it is probably a belemnite; if it shows a honeycomb, it is probably bone; if it shows nothing at all, it is probably a pebble.

When in doubt, keep it, photograph it, and ask. Heritage centres at Charmouth and museums on the Isle of Wight and in Norfolk will identify finds, and most are pleased to be asked.