More Weirdness from Mars

The latest odd-looking rock found by the Spirit rover is dubbed "Pot-of-Gold." It looks like this in low-angle light, but in other images it appears fairly flat. My guess is that it's some sort of caliche, a subsoil crust familiar to landowners in dry regions. Once exposed at the surface, the delicate erosion of Mars's dusty winds has sculpted it into a veritable fairy castle. But the Mars mission scientists are being more careful about identifying it. See the full-sized version of this image plus more at the Mars mission site.