Here's a picture of some of the unexploded WW1 ordinance that is regularly unearthed in France and Belgium.
Imagine going out to your garden to dig a spot for daisies and finding that instead!! We find Indian pottery shards here in Arizona, maybe an arrowhead ... NO ordinance! Good Lord. Imagine children playing ... we tried to dig to China when I was a child, my sister and I ... that was on Long Island and what we found was nothing more sinister than sea water LOL put an end to our digging to China. We couldn’t understand how Chinamen weren’t all drowning.