Rare $1 coin 'Mob of Roos' coin is worth up to $2,000 because of one strange detail

A rare misshapen $1 coin could net a lucky owner thousands of dollars.

Almost six million $1 coins designed by artist Stuart Devlin were minted in 2005, featuring his iconic design of five hopping kangaroos on the reverse side.

But a handful of the millions of 'Mob of Roos' coins made were bent out of shape due to an error in the minting process. 

The die used to impress the coins was off-centre, resulting in some of the kangaroos appearing as if they had their ears chopped off, while the other has a crescent-shaped blank space.

It is not known how many of the misshapen coins made their way into circulation but they have since become collectors' items, capable of fetching up to $2,000.

Error coin experts Mark Nemtsas and Kathryn Harris, who own and run The Purple Penny coin shop in Adelaide, said it was was uncertain why the mistake arose.

'This is not a common error by any means but if you do have a dollar coin that is struck off-centre similar to the coin we're discussing here then there's a very high chance it's dated 2005 as a number of these have been found,' they explained. 

'Why this many? That is uncertain, but perhaps one or two die pairs were setup incorrectly for the production run.'

One of the coins is currently listed on Ebay for $1,850.