fossil

Fossil crinoid stem segment (columnal)

Crinoidea; commonly preserved as calcite ossicles, often called entrocrinite

AI-generated identification · may be incorrect

Fossilized, segmented cylindrical structure with repeated columnals and central canal; typically gray, tan, or brown, with dull to pearly calcite luster. Calcite has Mohs hardness 3, rhombohedral cleavage, and specific gravity about 2.7.

Identified August 8, 2026More fossil →

Explore Fossil crinoid stem segment (columnal) in the encyclopedia →

Identify your own rocks.

Get a report just like this from any photo, free.

App Store Google Play

Physical properties

Formation & geological history

Remains of marine crinoids (stalked echinoderms) preserved mainly as recrystallized calcite in limestone or carbonate sediments. Crinoids range from Paleozoic to Recent, and specimens like this are commonly Carboniferous or Ordovician, though exact age requires locality data.

Uses & applications

Primarily a collector’s specimen, teaching aid, and decorative fossil; it has little industrial value beyond the limestone matrix in which it occurs.

Geological facts

The apparent “beads” are individual skeletal plates joined into a living stalk; the central opening carried tissue and nerves. Dense accumulations of crinoid fragments can form crinoidal limestone.

Field identification & locations

Identify by the regular repeating segments, radial symmetry, and central lumen; a cross-section often shows a five-petaled or star-like pattern. Common in Paleozoic marine limestones worldwide, especially the United States and United Kingdom.