CRINOID FOSSIL

Crinoids thrived during the Paleozoic Era, which was 490 through 250 million years ago, and they reached their apex as a species during the Mississippian Period, 360 through 320 million years ago. The original name "Crinoidea" comes from the Ancient Greek word krínon, for "lily", with the suffix for oid meaning "like". Today, there are roughly 700 living species of crinoid, but the class was much more abundant and diverse in the distant past. In certain places across the world, geologists have uncovered thick limestone beds that are almost entirely made up of layers upon layers of crinoid fragments.  The sedimentary rock formations of this nature are often called encrinites. These encrinite crinoid columns can be so abundant that they sometimes serve as primary and supporting clasts to carbonaceous minerals, like calcite, within layers of sedimentary rocks. These crinoid beds date from the mid-Paleozoic era to the Jurassic period, with incredible and diverse development between 400-200 million years ago.

CRINOID, LIVING FOSSILS

Crinoids are considered a living fossil, and are classified as echinoderms commonly related to starfish, sea urchins, brittle stars, and sea cucumbers. Crinoids that remain attached to the sea floor are commonly called sea lilies. Many crinoid traits are like other members of their phylum; Such traits include tube feet, radial symmetry, a water vascular system, and appendages in multiples of five (pentameral). They live in shallow water, as well as within incredible depths as great as 30,000 ft. Crinoids tend to feed by using their long, feather-like arms to grab and filter plankton and small particles from the sea water flowing past them. The arms are raised to form a fan-shape which is held against the current. Certain crinoids have the ability to maximize their feeding opportunities by moving around to better perch on rocks or coral heads. In 2005, a mobile species of stalked crinoid was recorded pulling itself along the sea floor off the Grand Bahama Island, just 45 miles south of Palm Beach, Florida. While it has been known that the stalked crinoid species could move, before this recording the fastest motion known for the species was 2 feet per hour. The 2005 recording showed this crinoid moving across the seabed at a much faster rate than thought possible, moving at a pace of 1.6 to 2.0 in per second, or 472 to 591 ft per hour.

CRINOID HISTORY AND FACTS

Historically, fossilized crinoid column segments that were pulled from the limestone quarry on the tidal island of Lindisfarne, or “Holy Island”, in England were once threaded into necklaces and rosaries; during the Middle Ages, these crinoid beaded ornaments later became known as St. Cuthbert's beads. Similarly, in the Midwestern United States, fossilized crinoid columns have been faceted and polished; these are sometimes called Indian beads, or Native beads. Additionally, a specific species of crinoid, Eperisocrinus missouriensis, is considered the state fossil of Missouri. Interestingly, is has been stated that the aliens from the famed sci-fi thriller “Alien” movie franchise gained its original inspirations from crinoids.