Beautifully Detailed Blastoid
Blastoids were echinoderms, related to the modern star fish and modern deep sea crinoids.
They were stalked suspension feeders, filtering food particles out of the water column.
The theca (top part, bulbous structure) of a typical blastoid was attached to a column which was made up of a varying length stack of disc-shaped plates.
The mouth was located at the tip of the theca. The top views below clearly show the ambulacara, the radiating structures coming from the center.
There were five food grooves, or ambulacara in Blastoids.
Each ambulacra had very fine long and thin structures called brachioles, with which they would trap food particles, organic matter floating in the water column or plankton etc.
Due to the delicate nature of the Brachioles they are not normally found intact on the fossil blastoid.
The Blastoid is .52 inches by .39 inches on a irregular matrix 1.57 inches by 1.76 inches.
St. Clair County, Illinois
This is the specimen you will receive.