How big could ammonite grow to be?

Ammonites, which are extinct marine mollusks, could vary significantly in size, with some species reaching impressive dimensions. The largest known ammonite, Parapuzosia seppenradensis, could grow up to 2.5 meters (about 8.2 feet) in diameter. However, most ammonites were much smaller, typically ranging from a few centimeters to about one meter in size. Their diverse sizes reflect a wide range of adaptations to different marine environments during the Mesozoic era.