What is "rotularia"

Rotularia is an extinct genus of planispirally coiled fossil polychaete worms in the family Serpulidae. Owing to the gastropod-like shape of Rotularia, many authors in the past interpreted this genus as being sea snails in the family Vermetidae.

All Rotularia species were cemented to the substrate during their earliest growth stage, but they became detached shortly after the formation of the first whorls (Savazzi, 1995). Their tubes have two layers with different microstructure (Vinn, 2008). This genus is known from the early Kimmeridgian to Late Eocene (Jäger, 2004).