Look closely and you can see beautiful wavy lines on this shell, known as suture lines. The ammonite shell was divided into chambers, and where the chamber wall met the shell, it folded like a curtain to create this lacy pattern. The last whorl of the shell is only partially preserved and has no suture lines.
The name Rasinia comes from the town of Market Rasen in Lincolnshire. This is where the Kimmeridge Clay was once quarried and the ammonite was discovered.
Find out more about ammonites on the molluscs pages.