 In the field , Calbovista puffballs are sometimes difficult to reliably distinguish from Calvatia sculpta . Although the latter species has prominent pyramidal warts , some specimens of Calbovista ( especially young ones ) may share this feature and the distinction between them becomes blurred . Microscopic differences can be used to tell the two species apart : Calvatia puffballs do not have a highly branched and entangled capillitium . Another lookalike , Mycenastrum corium , has a smooth peridium , a reduced or absent base , tends to split open in maturity into irregularly shaped sections , and has spiny capillitial threads . Calvatia subcretacea , also found in high elevations under conifers in western North America , has smaller fruit bodies , measuring up to 4 cm ( 1 @.@ 6 in ) high and 5 cm ( 2 @.@ 0 in ) wide . It has small pointed warts with gray tips . Calvatia booniana is a large puffball — up to 60 cm ( 24 in ) in diameter — found in open pastures and grassy areas of the western United States that has flat polygonal scales on the outer peridium . In addition to its larger size , it differs from Calbovista in that it lacks a sterile base and its capillitia are less branched and have septa . 
