A lucky tooth turned out to be the opposite for a passenger, when detector dogs sniffed it out in her handbag as she arrived into Queenstown Airport.
The dog alerted Ministry for Primary Industries (MPI) staff to the tooth brought to New Zealand by passenger arriving from China.
The woman's travelling companion explained it was a dog's tooth bought from a store in rural China she used for luck when she flew.
However, biosecurity staff was unsure.
"It looked way too big to be from a dog," MPI Central and South region border clearance manager Andrew Spelman says.
It turned out to be a tooth from a cow.
"The woman was fined $400 for failing to declare the item and had it explained to her that biosecurity was very important to New Zealand," Mr Spelman says.
"Under the worst case scenario the tooth could have been contaminated with foot-and-mouth disease, as China has had outbreaks of this devastating virus in the past. It could also have been carrying other diseases such as rabies, given its rural origin and the unknown circumstance of the cow's death."
He says the tooth was one of MPI's "more unusual" biosecurity interceptions at Queenstown Airport so far this year.
In May, a Mongolian woman was caught bringing yak meat into the country with a note from her daughter saying she was bringing food home.