Pentremites sp. blastoid collected from the Mississippian Big Clifty Formation of Indiana, USA. Pentremites belong to the class Blastoidea and they are a type of echinoderm. They resemble their distant relatives, the crinoids, being attached to the sea floor by a stalk, trapping food with tentacle like appendages. These specimens are available in two sizes: Small measure approximately 1 cm in total length and Large approximately 2 cm. Supplied in small plastic bags with an information label.