This is a good specimen of an edrioasteroid of the species Isorophusella incondita from the Verulam Formation of Canada. The genus Isorophusella often uses brachiopods as a hard ground fur settling. Probably in order not to be gradually buried in the sediment and to be transported piggy backed by the brachiopods to better feeding places.  It can be assumed that edrioasteroids and brachiopods utilize similar food sources.  
This Isorophusella incondita specimen measures about 16 mm in diameter.

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