Coal balls in North America were first found in Iowa coal seams in 1894,[3][4] although the connection to European coal balls was not made until Adolf Carl Noé (whose coal ball was found by Gilbert Cady[3][5]) drew the parallel in 1922.[2] Noé's work renewed interest in coal balls, and by the 1930s had drawn paleobotanists from Europe to the Illinois Basin in search of them.[6]