HALIFAX -- Renovators working on a 160-year-old home in Halifax have dug up a piece of the past.

When Michael Tompkins and his co-workers were ripping up floorboards and digging under the crawl space of the Halifax home they are renovating, they soon discovered the building featured some hidden history.

The crew found seven stones engraved with numbers and lettering, each weighing roughly 10 pounds.

Tompkins says he’s unsure if they are actually carved stones or made of cement.

“I thought they were gravestones,” says Tompkins.

Tompkins turned to social media in search of answers, posting pictures online and inviting history buffs to chime in on the origin of the stones.

“The page has been interesting, but I don't think there has been anyone yet to solve what exactly they are,” says Tompkins.

Historian David Jones loves a good mystery. He dug into the history of the more-than-100-year-old stones and says they were likely once part of a heating system.

“They were used in the construction of the roofs of furnaces and they were built by the American Arch Company, which was active at that time, and they had various patterns for similar technologies,” says Jones.

Tompkins says, as they continue to work on the home, he hopes they’ll discover more surprises.

“We haven't really even dug into the mud yet, the mud is going to be the exciting part. We will find some more treats I hope,” he says.