Nautiloids flourished during the early Paleozoic era, where they constituted the main predatory animals, and developed an extraordinary diversity of shell shapes and forms.
Some 2,500 species of fossil nautiloids are known, but only a handful of species survive to the present day.
Sutures (or suture lines) are visible as a series of narrow wavy lines on the surface of the shell, and they appear where each septum contacts the wall of the outer shell.
The sutures of the nautiloids are simple in shape, being either straight or slightly curved.
This is different from the “zigzag” sutures of the goniatites and the highly complex sutures of the ammonites

Miocene
Pietra Leccese Formation – Livello ad Aturia
Puglia, Italy
Very fine 30mm nautiloid on 64mm matrix
Nautiloid,