Orthoceras
Fossil
Also called Orthocone and Orthocerid
About it
Straight, cone-shaped nautiloid shells with a central siphuncle, best known polished in black limestone from Morocco. Those are Devonian orthocerids sold under the name; true Orthoceras is Ordovician, from Sweden and the Baltic.
- Type
- Fossil (mollusc)
- Group
- Cephalopod (mollusc)
- Colours
- black, grey, brown, cream
- Transparency
- opaque
- Periods
- Ordovician, Silurian, Devonian
Typical values: real specimens vary. For more, see mindat.org.