Placenticeras intercalare x5
Suture Patterns of the Ammonite: The inside of the shell is divided into a chambered part and an unchambered part. The body of the animal occupied the unchambered part, or living chamber. The chambered portion of the shell was divided by partitions called septa. Unlike nautiloids which have "straight" and simple septa. The contact of these septa with the external shell is called a suture.