The Australian half ounce silver piece (abbreviated as 1/2 oz and designated with Ag for "silver") is a bullion and commemorative coin format. Uniquely, in Australia there are two mints authorised to strike legal tender: the Royal Australian Mint (which also makes the country's circulating coinage) and the Perth Mint which only makes collector and bullion coins, as well as other bullion products.
Both mints endeavour to create coins with attractive designs, and to introduce new designs and themes often, in order to raise the numismatic value of the coins over the value of previous metal used.
The Mint says about this coin:
The fifth and final 1/2oz silver proof coin from the adorable Dreaming Down Under Series, this irresistible release portrays a baby wombat.
Equipped with powerful limbs and flattened claws, wombats are among the world’s largest burrowing animals. Like other marsupials, a baby develops inside its mother’s pouch, which in this species faces backwards for protection during digging. | 
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