BLASTOID Fossil Sea Life Echinoderm Mineral Specimen PAIR WIRE WRAP JEWELRY

Description

These specimens weighs 3.7 grams (average). They each measure about 19 mm x 13 mm x 13 mm.
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I am selling this really amazing pair of Pentremites robustus blastoid echinoderm fossils. I'm selling them as a "matched" pair especially for collectors and artists who might want to make a set of earrings out of these beautiful specimens. Every blastoid fossil is unique but I have carefully picked through all of my inventory to find two specimens that are as close to identical as possible. I bought them at a gem show in Arizona and they were found in the Glen Dean Formation, Crawford County, Indiana. These animals lived during the Mississippian Period, from around 358-323 million years ago! The details of these specimens are amazingly well preserved and absolutely stunning! They're really interesting and I hope they find a good home out there. Thanks so much for visiting my store and have a great day!
The following is information about this fossil from wikipedia:
Blastoid
From Wikipedia, the free encyclopedia
Blastoids
Temporal range: Ordovician - Permian
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Pentremites Glen Dean Fm KY.jpg
Pentremites godoni, a blastoid from the Lower Carboniferous of Illinois.
Scientific classification
Kingdom:
Animalia
Phylum:
Echinodermata
Subphylum:
Blastozoa
Class:
Blastoidea
Say, 1825
Orders
Fissiculata
Spiraculata
Incertae sedis:
†Macurdablastus
"Blastoidea", from Ernst Haeckel's Art Forms of Nature, 1904
Blastoids (class Blastoidea) are an extinct type of stemmed echinoderm.[1] Often called sea buds, blastoid fossils look like small hickory nuts. They first appear, along with many other echinoderm classes, in the Ordovician period, and reached their greatest diversity in the Mississippian subperiod of the Carboniferous period. However, blastoids may have originated in the Cambrian. Blastoids persisted until their extinction at the end of Permian, about 250 million years ago. Although never as diverse as their contemporary relatives, the crinoids, blastoids are common fossils, especially in many Mississippian-age rocks.
Contents  [hide]
1
Description
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Taxonomy
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References
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External links
Description[edit]
Like most echinoderms, blastoids were protected by a set of interlocking plates of calcium carbonate, which formed the main body, or theca. In life, the theca of a typical blastoid was attached to a stalk or column made up of stacked disc-shaped plates. The other end of the column was attached to the ocean floor by a holdfast, very much like stalked crinoids. The stalk was usually relatively short, and in some species, was absent, with the holdfast being attached directly to the base of the theca.
The mouth was located at the summit of the theca. Radiating like flower petals from the center were five food grooves, or ambulacra. Each ambulacrum had many long, thin, fine structures called brachioles, which were used to trap food particles and bring them to the mouth. Brachioles were delicate structures, and in fossils are not usually preserved in place. A series of five spiracle plates surrounded the star-shaped mouth, which included the anus, mouth and entrances to a set of five complex, folded respiratory organs known as hydrospires. These spiracles prevented mixing of the various fluids. Waste elimination was through the anispiracle, an opening formed by the fusing of anus and adjacent spiracles.
Pentremites godoni, a blastoid from the Lower Carboniferous of Illinois; basal view of theca.
Like crinoids, blastoids were high-level, stalked suspension feeders (feeding mainly on planktonic organisms) that inhabited clear-to-silty, moderately agitated ocean waters from shelf to basin. The food gathering system of blastoids consisted of several types of ambulacra. Food entered the brachiolar ambulacra, was transferred to the side ambulacra through the brachiolar pit, then transferred to the main (median) ambulacra, and finally entered the mouth. Each of these ambulacra was roofed by cover plates. The cover plates of the brachiolar groove were movable and could open, allowing food to enter, or close as needed. Other cover plates may also have been movable.
Taxonomy[edit]
See also: List of echinodermata orders
Blastoids are assumed to have evolved from the Cystoids. Blastoids are subdivided into two orders: Fissiculata, which are characterized by direct entrance to the individual hydrospires by way of slits; and Spiraculata, which are characterized by indirect entrance to the hydrospires through canals by way of pores. The earliest blastoid yet found, Macurdablastus from the Middle Ordovician of Tennessee, cannot be classified as either order.