The Mazon Creek H Creature - Problematic Etacystis communis

Name: Problematica: Etacystis communis

Geological Time: Pennsylvanian (~300 m.y.a.)

Size: 42 mm long by 41 mm across

Fossil Site: Mazon Creek - Pit 11, Francis Creek shale, Braidwood, Illinois

Mazon Creek H CreatureDescribed variously as a hydrozoan or a hemichordate, this most enigmatic of Mazon Creek taxa is colloquially termed the H creature. It is currently thought to have been a filter-feeding organism that grew throughout its lifetime, reaching a length up to 11 cm.

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