Here is a Large and well detailed HOLOCYSTITES scutellatus is an extinct echinoderm – relatives of the modern starfish. They were attached to the bottom of the sea floor by means of a short stalk.

Cystoid means “sac-like” referring to the bulbous portion of the creature called a theca. The theca is the main body and sits atop a column of round disk-shaped segments. The theca is comprised of a generally oval shaped body made up of geometric ossicles or plates. The theca contains all the internal organs as well as the mouth and anus.

Attached to the theca, the brachials or arms can be found. In some exquisitely preserved specimens the food capturing structures called pinnules are found well preserved. The pinnules were covered with small “tube feet” that would capture food particles as they floated by. Their food consisted of plankton, detritus and any organic matter that happened by. The particles would be conveyed towards the mouth and passed inside. This process was repeated over and over as food particles contacted the “tube feet”. The primitive digestive system would process these and then waste matter would be ejected through the anus located not very far from the mouth.

Due to the creature’s hard calcareous external skeleton fossilization and preservation exhibits great detail. This is especially true with the complete cystoids from the Rochester Shale.

Cystoids can be found in various numbers in locations and formations around the United States and the world. Generally they are found in sediments dating to the Middle Ordovician Period, some 460 million years ago, to the end of the Devonian Period some 358 million years ago.

Specimen was meticulously prepared using micro air abrasive technology. The cystoid is  1 3/4 inch long  by 1 1/4 inch wide.

Silurian Period
Niagaran Formation
Massie Shale
Napoleon, Indiana

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