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
Lincoln Creek Formation
Grays Harbor County, WA, USA
Extremely rare, large partial 67mm nautiloid preserved in chalcedony