The most famous Mars meteorite, the Allen Hills rock with its strange, cylindrical rock segments, may not be the most intriguing. Consider a rock launched from Mars only 700 million years ago called Lafayette. Judging by detailed chemical analysis, the outcome of Lafayette’s long journey to Earth points to a past where it might have been altered at the bottom of a salt-water pool. Or at least that conclusion is what many meteor scientists propose to describe what might have landed in North America about three millenia ago.