This could have been an explosive find.

Construction crews erecting a housing development in Colorado Monday unwittingly unearthed a piece of American history: a World War II-era bomb.

The cast iron “military ordnance” was found buried in Aurora in what was once the Lowry Bombing and Gunnery Range, the Arapahoe County Sheriff said this week.

Bomb squads were called in to investigate the relic, but X-rays revealed that the mini bomb posed no danger nearly a century after it was launched into the ground.

The device was identified as a Mark 23 Mod 1, which was one of three mini bombs used for bomb training during the Second World War.

Weighing 3 pounds, the bomb was mostly used for land targets, but could not be used against armored-deck target boats.

Experts are still cleaning up munitions from the former Lowry Bombing and Gunnery Range even as construction crews build a housing development, according to the Colorado Department of Public Health & Environment.

The property — which stretches about 100 square miles — was used as bomb training and military armament by the Air Force, Army, Navy and Air National Guard from 1938 to 1963, through the Korean and Vietnam wars.

The mini bomb found this week is now in the possession of the Buckley Space Force Base.