The skull of a black rat (right) compared with a fairly complete skull of one of Timor's other extinct giant rats (left). The giant rat shown here isn't the biggest of the extinct rats ...

No, this foreign invader is a snail. But what a snail it is. The giant African land snail "can grow as big as a rat and gnaw through stucco and plaster," says Reuters' Barbara Liston. Since the ...