Summary[edit] Description: English: Chiridotidae; fossil sea cucumber. Registration no. P 75336-1 Geospatial Information Continent : North America Country : United States of America State : Illinois District : Grundy County Town : Morris Era : Palaeozoic Period : Carboniferous Epoch : Pennsylvanian Stage : Moscovian Geological group : Kewanee Group Geological formation : Carbondale Formation Geological member : Francis Creek Shale. Source: Museums Victoria. Author: Photographer: David Bowers.