Great South Gems & Minerals

• Crinoid Stem Plate Fossil •
(Tennessee) 

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• Crinoid Stem Plate Fossil •
(Tennessee) 

Echinoderm - sea lilies - Phylum Echinodermata

Great looking fossil crinoid stems from Dale Hollow Lake, Alabama. Don't know the age of this material but it has to be very old. These specimens have turned to quarts.

Crinoids have an extremely long fossil record, beginning to the Ordovician period and lasting until the present time, a 500,000,000 million year record! The fossils here are the fossilized column, or stem part of the animal. Crinoids are called "sea lilies" because of its flowering-like tentacles at the crown,and are exclusively a marine animal. Though resembling a plant it is a member of the Phylum Echinodermata. Crinoids look like plants because the body skeleton, or calyx, generally grown on the end of a stem made of button-like arms.

Crinoid stems or separate stem discs are common throughout most countries of the world, and are found in many states within the United States. The fact that crinoid stems and individual disc sections are found throughout the United States is evidence that at one time most of the land area that now make up the United States was once under seas. Some crinoids live today, mainly in deep parts of the ocean, but they are not nearly so common as in the past.

Most crinoids had a foot-like bottom section called a holdfast or root that it used to anchor itself to the sea floor. Above this foot-like section was the stem that supports the animals crown of arms that waved with the ocean movement. At the center of this crown of arms is the calyx, which contains the vital organs of the animal. The calyx is small when compared to the total mass of the crinoid, most of which is devoted to food collection. The mouth and anus are located on the upper surface of the body, and are connected by a simple gut. The arms at the crown are composed of an articulated series of ossicles that are used in suspension feeding and respiration. The gonads are also located in the arms; fertilisation takes place in open sea water during mass spawning.

While most crinoids were stalked animals, rising from the sea floor with their stems, there are a number of species that are "free floating" crinoids, not being anchored to the sea floor. Scientist believe that during the long span of time that crinoids have existed, that there have been over 600 species.

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