Sutures and chambers
Ammonites are divided into a series of chambers by walls that become highly folded as they meet the edge of the shell. This creates the wavy suture lines – in this example, the shell has broken away to reveal these beautiful patterns. The black paint illustrates the chamber, now filled with sediment, between two chamber walls marked by two parallel but intricately-folded suture lines.
Find out more about ammonites on the molluscs pages.