Designer: obverse: Arnold Machin; reverse: Stuart Devlin
Reference: KM# 66
Diameter: 28.5 mm
Reverse The central area features a relief image of a swimming platypus and large numerals '20'. To the left is the inscription 'SD' — the engraver's mark of Stuart Devlin.
Obverse On the left, following the curve of the coin's edge, is the English text 'ELIZABETH II'. On the right is the country name Australia and the year of issue 'AUSTRALIA 1971'. The central area features the right-facing profile of Queen Elizabeth II.