Designer: obverse: Arnold Machin; reverse: Stuart Devlin
Reference: KM# 66
Diameter: 28.5 mm
Reverse A platypus and the numeral 20 are depicted against a background of water ripples. To the left of the aquatic mammal are the designer's initials, Stuart Devlin - 'SD'.
Obverse In the central part is a right-facing profile of Queen Elizabeth II of Great Britain wearing a crown. On the left, following the curve of the coin's edge, is the monarch's name 'ELIZABETH II'. On the right is the name of the dominion 'AUSTRALIA' and the year of issue '1973'.