Here is a fossil jellyfish of the species Lascoa mesostaurata from the classical Lagerstaette of Mazon Creek in Illinois. This fossil shows a reprehensive preservation as it is not unusual for this fossil site. The concretion how ever is very nice developed.
|Mazon Creek, Braidwood, Illinois , USA|
|Size of concretion :||about 70 x 61 mm|
|Age:||Upper Carboniferous, Pennsylvanian , Carbondale Fm. (about 300 Ma)|