Sphenothallus sp.
Worm
Ordovician
Collingwood Member, Lindsay Formation
Bowmanville, Ontario, Canada

47mm worm tube on 63mm shale. Rare.

Sphenothallus is a genus that has been a distinct challenge for researchers to assign to a particular group.  It has been considered a cnidarian, a worm, and it has been left “incertae sedis”, which is the Latin term meaning that its relationships to known groups are unclear or unknown.  Whatever it is, its simple morphology makes it difficult to make a call on it.  Similar remains have been found from the Ordovician to Carboniferous of North America and Europe but it is quite rare wherever it is found.

A specimen for the collector of truly ancient trace fossils – ancient mysteries.