Archimedes
Fossil
Also called Archimedes screw
About it
Screw-shaped central axis of a lacy bryozoan colony, named for Archimedes' screw; the lacy fronds are usually lost. Common in Mississippian limestones of Illinois, Kentucky, Alabama, and Arkansas.
- Type
- Fossil (other)
- Group
- Bryozoan
- Colours
- grey, tan, brown, white
- Transparency
- opaque
- Periods
- Carboniferous
Typical values: real specimens vary. For more, see mindat.org.