Description

Thoralicystis zagoraensis
Early Ordovician (Arenigian)
Upper Fezouata Formation
Zagora, Draa Valley, Morocco
107mm slab with at least 4 excellent specimens plus partials. Largest is 17mm.

Echinoderm. Soft-bodied. Multiple.

Thoralicystis has been classified as an echinoderm within the Class Stylophora because of the structure of its test though it lacks the fivefold symmetry of most echinoderms.  Some paleontologists claim it is a primitive chordate because it appears to bear a notochord in its tail.  However, it lacks the bilateral symmetry seen in chordates. It might end up being interpreted as a relative of early echinoderms and/or chordates. Whatever it is, it’s known only from the Ordovician of Nevada, parts of Europe, and this occurrence in Morocco.

In any case, here’s a cool piece with several specimens on it.