1.5" Fossil Worm (Astreptoscolex) - Illinois

This is a 1.5" fossil worm (Astreptoscolex) preserved in an ironstone nodule from the Carbondale Formation near Essex, Illinois.

Astreptoscolex anasillosus worms are a medium-sized polychaete that has a rounded body that tapers toward the tail. It had an eversible proboscis that carried a small set of jaws, as well as gills that are sometimes visible with nice preservation. It was likely that this worm had a tough hide or cuticle which would explain the commonly detailed preservation.