1. Many gastropods are grazers: they use their radula to rasp away at algae.

2. Unlike other molluscs , bivalves lack a radula and feature labial palps, which carry food from the gills to the mouth.

3. "Ammonites used their radula to trap the food in the mouth and convey it through the esophagus, " Kruta explained.

4. The researchers determined ammonites possessed jaws and a radula, which is like a tongue covered with teeth.

5. They have no skeleton, instead relying on an internal mantle that supports and shapes the head, while a specialized radula deep in the throat shreds food in preparation for digestion.