Crinoid "Feather Stars" Columnal Segments
Crinoid "Feather Stars" Columnal Segments
Crinoids are an incredible group of aquatic animals that attach themselves to the seafloor and filter feeds with beautiful feathered arms. These creatures are echinoids, an ancient and varied group of life. Crinoids emerged in the fossil record over 541,000,000 years ago and some species still exist to this day.
This specimen is a fossilized Crinoid stem segment that dates to the Jurassic Period. The animal's stems were made of individual endoskeleton pieces that exhibited 5 way symmetry. These pieces were held together by ligaments which decayed and spread the segments after the crinoid died and was fossilized.
Each fossil Crinoid segment specimen contains 5-7 segment pieces, carefully arranged in an acrylic jar set into a display case. An informational card which serves as a certificate of authenticity is also included.
Strange Sea Animals
Sometimes referred to as feather stars or sea lilies, Crinoids are members of an extended and very ancient family of sea animals known as echinoderms. Echinoderms date back as far as the Cambrian period some 541,000,000 years ago. They include such varied animals as sea urchins, sea cucumbers, and starfish.
The evolution of crinoids was part of another explosion of complex life on Earth during the Ordovician, which resulted in most of the animal or metazoan body plans we know today. Early crinoids looked like undersea flowers, with root-like feet, a segmented columnar stalk, and feathery arms at the head which could filter and toss floating food towards the mouth.
This specimen is a hand-selected assortment of crinoid stem segments, also known as "columnals". In life, these endoskeleton segments would have been stacked on top of each other with soft ligaments to create a long and flexible stalk for the crinoid to drift in the sea current. Now fossilized, they show the 5-way radial symmetry that was unique to echinoid body plans.
📸 An illustration of a crinoid on the ancient seafloor. This fossil made up the central stalks of these creatures.
These crinoid fossils were recovered near Talsint, Morocco. The fossil beds in this region are from the Bajocian Age of the Middle Jurassic Period and date to roughly 170,000,000 years old.
The specimens come inside an acrylic specimen jar, encased in a classic, glass-topped riker display case measuring 4 1/2" x 3 1/2". A small information card is also enclosed that also serves as the certificate of authenticity.
Please Note: Each specimen will be unique with varying degrees of detail. Pictures included on this page are representative one. Each jar should have 5-7 segments depending on their size.
ORIGIN: 541,000,000 years ago
MORE ABOUT Crinoids
📸 Crinoid drawings by Ernst Haeckel from "Kunstformen der Natur" (Art Forms of Nature, 1904)
While crinoids resemble plant life at first glance, they are actually animals with quite complex lifestyles. A variety of feet have been found with different species, some with root-like structures and others with curling limbs. Sprouting from this base is a long segmented stalk that ends in the crinoid's mouth and arms. These arms are covered in tiny branches that secrete sticky mucus to capture floating food particles.
Breaking down body plans into their simplest form involves looking at a concept known as symmetry. Symmetry in biology means that bodies can be divided in various ways which are more or less identical to each other.
There are three very basic forms of symmetry in biology: bi-lateral, spherical, and radial. Humans exhibit bilateral symmetry, with our bodies organized along a centerline. Spherical symmetry is generally limited to very small organisms like algae which form spherical colonies. The last form, called radial symmetry, is a bit like a pie where body parts are arranged around a central axis.
There are a number of variants to this radial symmetry wherein body parts are separated into four, five, six, or even eight symmetrical pieces. Echinoderms are the only animals that exhibit the five-part, or pentaradial form of radial symmetry. This body plan also happens to result in interesting fossil shapes.
📸 A modern day crinoid
Floating Feather Stars
Many crinoid species still exist to this day, with modern species surviving into adulthood without their stalks. Once their growth is complete, they detach from their segmented stems and swim through the ocean as free-floating "feather stars."
This life cycle change is thought to have become common around the Triassic period, but tracking the evolution of stem detachment is tricky. The crinoid's arms are made of soft material which can decompose quite quickly, while the endoskeleton of the stem fossilized far easier. Much of the fossil evidence of prehistoric crinoids we have today come from either these column segments or mass die-off events.
📸 A more complete crinoid fossil. You can see the segments of the column in the stem here.
Crinoid Fossils in History
Before they were identified as fossils, segmented Crinoid stems were sometimes referred to as "fairy money". This is not so different from the way other fossils were viewed, such as "snake stones" (fossil ammonites) or "snake tongues" (fossil shark teeth).
Crinoid stems also worked their way in Christian legends in both Germany and England where they were known as St. Boniface's pfennige (pennies) and St. Cuthbert's beads. The latter is particularly interesting in the context of the Mini Museum as St. Cuthbert was a 7th-century monk on the island of Lindisfarne off the coast of Northumberland. If you'll recall, the Vikings raided this island in 793 just 100 years after the death of St. Cuthbert, for whom the monastery there is named.
Front of the Specimen Card
Back of the Specimen Card
Chambers, Robert. The Book of Days, a Miscellany of Popular Antiquities. 1862.
Hess, Hans, et al. Fossil Crinoids. Cambridge University Press, 2003.
Kelley, Patricia, Michal Kowalewski, and Thor A. Hansen, eds. Predator-prey Interactions in the Fossil Record. Vol. 20. Springer Science & Business Media, 2003.
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