Niue, a sovereign state in free association with New Zealand, uses two official legal tender currencies. The New Zealand Dollar is the circulation currency for daily transactions, while the government also authorises legal tender coins in the Niue Dollar currency for collector's purposes.
A number of mints issue a large variety of commemorative, bullion and collector coins under the authority of Niue. These coins are dedicated to historical or general popular culture themes not related to Niue itself. Many of them are in standard bullion sizes - typically, one ounce of silver (abbreviated as 1 oz Ag, where "Ag" comes from the Latin word for silver, Argentum). Many of these feature various animals.
This coin is part of a series by the Mint of Poland dedicated to butterflies, and depicts a Goliath Birdwing butterfly.
The Mint says about it:
"The fifth issue in the captivating Butterflies series of silver coins bears the title “Goliath Birdwing” and is dedicated to one of the largest butterflies in the world inhabiting the tropical rain-forests of Papua New Guinea. This butterfly got its name due to its large wings that can measure up to 28 cm and the bird-like style in which it flies. Thanks to the pad printing technique the image on the coin displays the genuine colours of the butterfly. To the right of the image, there is the inscription denoting the Latin name of the insect." | 
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