This spiral is one of the oldest designs in nature — a shell that was drawing its own golden ratio 150 million years before mathematics named it. The ammonite was the nautilus of the dinosaur age: a shelled predator that filled the ancient seas, coiling into the perfect spiral you see here. When it died, its shell sank into the seabed and — over millions of years — was replaced, mineral by mineral, until the whole spiral turned to stone. This specimen, QS004, is a genuine, natural ammonite fossil: The classic spiral shell, 10 × 8.5 × 2.3 cm, complete in its coiling form. An iridescent sheen across parts of the surface — soft rainbow colours that shift as the fossil turns in the light, the result of microscopic mineral layers in the shell. Visible suture lines — the delicate ribbed texture of the shell's chambers, clearly preserved. Natural surface character: parts of the shell carry attached rock matrix, and there are natural chips and a hairline crack revealing the inner matrix beneath — honest traces of its long journey from the seabed to your hand. Weighing just 0.25 kg, it sits comfortably in the hand — the kind of specimen that makes people turn it over, tilt it to the light, and watch the colours play. Whether you collect fossils, teach natural history, or simply love the deep time written into the earth — this ammonite is a genuine, untouched piece of the Mesozoic, ready for a shelf, a desk, or a specimen box. Specifications: Type: Genuine ammonite fossil Reference: QS004 Size: 10 × 8.5 × 2.3 cm Weight: 0.25 kg Features: Spiral shell, iridescent sheen, visible suture lines Condition: Natural specimen; surface chips, attached rock matrix and a hairline crack present (shown in photos) Age: Mesozoic (fossil) Origin: Natural specimen, not artificially treated It is a spiral older than mathematics, with rainbows in its stone, resting in your hand. You get to display it