In a B movie, a marauding mollusk would probably be played by a giant clam. But the real-life monster swimming amuck in the Great Lakes is a tiny creature the size of a fingernail. With its jaunty brown stripes, a solitary zebra mussel looks cute, not threatening. The trouble is that the animal is anything but a loner, and its tendency to form colonies of thousands, even millions, makes it threatening indeed.
Unknown in North America until 1988, the zebra mussel has become a pest whose exploding population has prompted alarming predictions of millions of dollars' worth of damage to water-supply...