Near Amy, Randy can see another silt-covered boulder near the surface, maybe six...

Near Amy, Randy can see another silt-covered boulder near the surface, maybe six feet away. He gathers himself and leaps towards it. But it topples under the impact of his foot and sends him splashing full-length into the streambed. When he sits up and gets a look at it, the boulder turns out to be a squat cylindrical object about as big around as a dinner plate and several inches thick.
'Randy, what you're looking at is a Nip anti-tank mine,' Doug says. 'It is highly unstable with age, and it contains enough high explosive to essentially decapitate everyone in our little group here. So if you could just stop being a complete asshole for a little bit, I'm sure that we would all appreciate it very much.