Goniatite

These beautifully preserved simple ammonites are easily recognised from other species of ammonite by the zigzag suture pattern between each section of the fossil.

Each chamber is the result of the way the creature grew; starting life in the centre as a tiny hatchling, as it got bigger, it created a thin septa or chamber wall behind itself which over time, built the spiral we see in the fossilised remains. The living animal always inhabited the largest front chamber building up the shell throughout its life span. The largest found are about 15 cm across.

The empty chambers behind the living Goniatid were filled with gas that gave buoyancy to the animal. It fed through a narrow tube from its location in the front chamber although it remains unclear what they actually ate or how long each individual lived, we do know that they lived in shallow areas of ocean in locations that would have tropical or sub-tropical at that time.