COEUR D'ALENE, Idaho (AP) — An 8-year-old boy has found what appears to be a cannonball in northern Idaho.

The Coeur d'Alene Press reports that though the boy says he had thought it was a dragon egg, Museum of North Idaho historian Robert Singletary says it appears to be a cannonball fired from Fort Sherman.

Fort Sherman was built in Coeur d'Alene shortly after the Civil War to keep Native Americans from interfering with construction of the Continental Railroad.

Singletary says the cannonball was found 1.8 miles from the edge of the fort — farther than a cannonball could fly — but that troops would leave the fort to practice and perhaps the cannonball was from one of those exercise.

The Museum of North Idaho is keeping the cannonball and will find experts in late-1800s artillery.