A saltwater crocodile on Thursday found in the Australia's Northern Territory has been described as a "freak of nature."

The half-meter long reptile has sharp spurs protruding from the underside of its back legs. The five millimeter-long spurs connect to a bone stemming from the crocodile's ankle joint.

Crocodile hunter Mick Pittman displays the crocodile's extra toes. [ABC news]

"I don't know whether a croc's been playing up with a platypus or not, but it looks a bit funny, I reckon," crocodile hunter and taxidermist Mick Pittman told The Australian on Thursday.

"I've never seen anything like it."

Pittman, known as "Crocodile Mick," said he and his family have been in the crocodile industry for 53 years. He thinks the spurs might be mutant toes.

"I reckon the way it was sitting on his leg, it would have to hinder his existence," he said.

"He would have to be scratching himself all the time when he was walking. You can't see any real use for it. It's just a freak of nature."

Dr Grahame Webb from Crocodylus Park in Darwin said the spurs are extremely rare.

"I've seen it once or twice in looking at tens of thousands of hatchlings," Webb told The Australian.