Sutured Ammonite Fossil

Ammonite, which means coiled horn, was a prehistoric air breathing invertebrate. It looked like an ancestor of the squid except its body was protected by a shell which it grew by adding chambers in a spiral pattern. The shell is divided into chambers separated by walls called septa, strengthening the shell. The term suture pattern refers to the featured line that makes contact with the septa and the interior of the shell.