columnals

Columnals are fossilized remains of ancient marine animals belonging to the Crinoidea class, commonly known as sea lilies or feather stars. These animals were sessile during their adult stage, attaching themselves to the seabed by a stem. The stem was segmented, and each segment is called a columnal. These segments are often found as individual fossils, particularly in sedimentary rocks of Paleozoic and Mesozoic age.

Columnals are typically disc-shaped or star-shaped, with a central pore or canal. Their exact shape and size can vary depending on the species and the position of the segment within the stem. The porous internal structure, known as the stereom, is characteristic of echinoderms. Over time, these segments became mineralized, preserving them as fossils.

The study of columnals provides valuable insights into the paleoecology and paleobiogeography of ancient marine environments. Their abundance in certain rock layers can indicate periods of high crinoid populations and specific environmental conditions. Because of their distinct appearance and widespread distribution, columnals are often used as index fossils, helping geologists to date rock formations. They are frequently collected by fossil enthusiasts and are common in museum collections.