THOMASTON – A mortar like the one detonated this week by state police is no keepsake, Police Chief Kevin Haj said Wednesday.

He reminded people to be cautious when finding old explosives.

The rusted mortar, measuring 1 foot long and up to 4 inches in diameter, was found Monday by a worker in a house. It may have dated from World War II or the Korean War era.

It was wedged in the studs of a barn at 411 Main St., across from the site of the former Maine State Prison. It was reported to police at 2:15 p.m. Monday.

Haj said the device was shaped like an inverted pear with fins on it.

Members of the Maine State Police bomb squad took the round to George C. Hall & Sons gravel pit off Beechwood Street on Monday and blew it up, Haj said.

The house where the mortar was found has been vacant for about a year, according to Haj. The property is owned by Jeanine Griffin and Thomas Roach.

Maine State Police Sgt. Jeff Mills and Trooper Trevor Snow handled the mortar by countercharging it “with some of our explosives,” Mills said Wednesday.

The mortar appeared to have explosive in it, he said, but it did not have a detonator.

“These things can lay around for 40 or 50 years,” Haj said. “It was so rusted [police] couldn’t get numbers on it,” he said. So they could only guess how old it was.

Haj cautioned people who find “old war trophies” not to play with, pick up or move them.

“Please don’t bring them to the police station,” Haj said. “We’ll come to you.”