As they comb the area, one of them will spot a distinct gleam of silver sticking out of the rocks and the mud on the riverbank. But just as someone points it out, it dislodges from the bank! It's heavy enough that it doesn't move as fast as the branches and organic debris near the surface. It's also simple enough to track, the sun is bright overhead and the silver metal shines even close to the bottom of the river.

How do they proceed? :)