Coprolite with Unidentified Chitinous Ring Inclusions

Mysterious Crap Circles
Chitinous ring
Orton Pit Peterbourough, Cambridgeshlire, England
United Kingdom

At first glance, these ring-shaped inclusions appeared to be fish vertebra. However, under magnification, a rather unique surface texture can be seen. Unlike phosphatic bony fish vertebrae, these seem to be comprise of chitin, the same material that makes up things like crustacean exoskeletons, and cephalopod limb rings, hooks and beaks. So what are they? Well, this remains a mystery. Here are some of the things we considered:

Sucker rings from cephalopods: The suckers of some cephalopods, such as the Humboldt squid, have chitinous rings that help the animal grip slippery food. However, the rings found in this coprolite lack the "teeth" or serrations found in those of modern squid.

Radulae: Mollusks, including some cephalopods, have rows of tiny teeth known as radulae. However, we have not been able to identify ring-shaped radulae.

Lobster antenna segments: This possibility is currently being explored. Stay tuned.