<p>Pentremites sp. - fossil blastoid head in the Mississippian of Kentucky, USA.
</p><p>Blastoids are an extinct group of echinoderms.  They resemble crinoids in having a head, or theca, perched atop a long stem of stacked columnals composed of calcite.  Crinoids and blastoids are pelmatozoans - stalked echinoderms.  Both groups are sessile, benthic, filter-feeding organisms.  The overall structure and morphology of crinoid heads and blastoid heads are quite different.  Blastoid heads have pentaradial symmetry and somewhat resemble closed flower buds or nuts.  They have five ambulacral grooves extending outward and downward from the summit of the theca.  During life, many thin, delicate brachioles extended from the ambulacral grooves - these structures captured tiny particles of food from seawater as the blastoid engaged in filter feeding.
</p><p>Classification: Animalia, Echinodermata, Blastozoa, Blastoidea, Spiraculata, Pentremitidae
</p><p>Stratigraphy: shale-rich interval in the Ramey Creek Member, Slade Formation, Chesterian Series, Upper Mississippian
</p><p>Locality: roadcut next to the Route 1274-Route 801 intersection, southwest of the town of Morehead, Kentucky, USA. (vicinity of 38° 04’ 51.58” North latitude, 83° 25’ 21.64” West longitude)
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<hr><p>More info. at:
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&lt;a href="<a class="external free" href="https://en.wikipedia.org/wiki/Blastoid">https://en.wikipedia.org/wiki/Blastoid</a>" rel="noreferrer nofollow"&gt;en.wikipedia.org/wiki/Blastoid&lt;/a&gt;
<a rel="nofollow" class="external text" href="https://www.flickr.com/people/47445767@N05">James St. John</a>
CC BY 2.0
<a rel="nofollow" class="external text" href="https://www.flickr.com/photos/jsjgeology/31049574517/">Pentremites sp. (fossil blastoid) (Ramey Creek Member, Slade Formation, Upper Mississippian; Rt. 1274-Rt. 801 outcrop, southwest of Morehead, Kentucky, USA)</a>