Slowing down decay
Called Eoderoceras, this is probably the largest ammonite preserved in iron pyrites that can be picked off the beach in a perfect state. There is a down-side though – pyrite ammonites can decay because the iron sulphide is unstable on contact with oxygen in the air. The best solution is to keep the specimens somewhere dry to slow the process down.
Find out more about ammonites on the molluscs pages.