This all encompasing group includes organisms whose evolutionary lineage is unclear or unknown. They are organisms present in the fossil record, but it is unknown where they came from, and often unknown how they relate to one another.
Animals within this group include:
- Tentaculites is an extinct genus of conical shelled fossils. This only appears in Lower Ordovician to Upper Devonian fossiliferous deposits. The lineage for Tentaculites is unknown, but it has a microstructure similar to brachiopods and carbonaceous linings. They are ribbed and cone-shaped, ranging from 5-20 mm in length.
- Cornulites is believed to be a genus of tubeworms. They are generally found encrusted on other fossils, and are present from the Middle Ordovician to the Carboniferous. Like Tentaculites, their lineage is unknown.