Found this inside a friend’s dead USB memory stick:
The leads come from a teeny 12 MHz crystal. The solder blob on the other side looked just fine, but you simply can’t tell by looking.
As it turned out, the stick was dead for some other reason: the Flash memory controller chip got hot when the stick was drawing power. Resoldering all the joints had no effect, which wasn’t surprising.
I suspect a killer static discharge or some such calamity.