Liz and Rob Virtue were expecting to find rats in their roof, not a hidden tobacco pipe designed to ward off evil spirits.

The pair run Glen Derwent estate, a 200-year-old Georgian farmhouse at New Norfolk west of Hobart.

When Mr Virtue went up into the roof to solve his rodent problem, he was amazed to discover the handcrafted clay pipe concealed between two bricks.

The pipe was found in the roof of the 200-year-old house. ( Supplied: Liz Virtue )

"It's just so amazing," Mrs Virtue told Helen Shield on ABC Radio Hobart.

"We haven't decided what to do with it yet."

The house was built by ex-convict James Bryan Cullen, and the Virtues are in contact with some of his descendants, some of whom suggested the pipe should be put back.

Historian Ian Evans believes its concealment was part of a superstitious ritual — a theory that took the Virtues by surprise.

Coins found under the house's floorboards earlier this year are also believed to be part of an evil-averting custom.

Warding off 'nasty beings'

Dr Evans is behind the Tasmanian Magic Research Project which records evidence of the culture of magic in Tasmania during the 19th century.

The project investigates evil-averting marks on houses and concealed objects — a practice with a long history.

"It dates back many centuries. We haven't actually traced the very beginnings of it, but it's known to have happened in England for eight centuries," he said.

Other evidence of evil-averting rituals has been found at the New Norfolk property. ( Supplied: Liz Virtue )

Dr Evans began searching for evidence of the rituals in 2003 and said they had been brought to Australia by convicts and colonial settlers.

The Virtues' pipe was the first he'd seen concealed in such a manner anywhere in Australia.

"I thought it was very clearly a deliberate concealment of an artefact, the purpose of which is to divert unpleasant spiritual beings from the humans in the house to these objects.

"If these beings could be lured into voids in a building, they would not be able to escape and therefore not be able to harm the humans who lived there.

"I've had truckloads of old shoes, garments, dead cats, household goods — but this is the first pipe."

Ian Evans began searching for evidence of rituals in 2003. ( ABC News: Scott Ross )

Dr Evans said there was no literature documenting the practice nor explaining it.

"We are left to decipher this from the objects that are found," he said.

"We can only conclude that it was a technique they thought would help save them from nasty unpleasant beings seeping into our world from the underworld where the devil reigns supreme."

Other symbols of magic had been found around Glen Derwent, Dr Evans said, such as concealed shoes and interesting marks punched into brass strips on front doors.

His most memorable artefact was the skull of a Tasmanian devil used in a house near Campbell Town.

"It was concealed and in the same category as the pipe," he said.