Plymouth, Mass. ? The owners of a furniture warehouse in Plymouth, Mass., want to know the origin of a chunk of metal that plunged through the roof.

No one was hurt when the 6-inch, cylindrical piece of metal weighing about 5 pounds came through the roof Wednesday or Thursday. The chunk punched a small hole in the roof over a closet and scattered ceiling-tile debris.

Federal Aviation Administration inspectors say the piece of metal was broken at both ends and was not an airplane part.

An FAA spokeswoman says the chunk likely came from a piece of heavy machinery, possibly a wood chipper. That still doesn’t explain how it came crashing through the roof.

Police are also stumped.

The owner of Michael’s Furniture Warehouse says someone could have been killed.