ANCHORAGE (AP) — Military officials in Alaska are warning the public that if they see a weathered metal object outdoors, they should not pick it up, but instead should call authorities. Such objects could be live explosives.

“If you don’t know what it is and it gives you any concern or suspicion, take a picture of it, leave it and call police,” said 1st Sgt. Marshall Pratt with the 716th explosive ordnance disposal company at Joint Base Elmendorf-Richardson. “If you don’t have a camera, don’t go get one and go back.”

The ordnance-disposal company has responded to at least 18 calls since October, the Anchorage Daily News reported.

It’s hard to differentiate explosives from ordinary litter, Pratt said.

Military officials have found heavy World War II artillery used as doorstops, displayed on mantles or stored in attics.

Last year someone called authorities after having second thoughts about an estate-sale purchase. The items were two rusted mortar rounds, said 1st Lt. Steve Latulipe with the ordnance company.

Military professionals destroyed the rounds.

Also last year, a couple walking along Point MacKenzie beach came upon a foot-long artillery round.

Pratt and other soldiers responded, stopped air traffic for 15 minutes, and blew up the artillery piece. The explosion sent a smoke plume more than 70 feet into the air.

“To the untrained eye, it would look just like a rusty piece of pipe,” Pratt said.