After seven years of roaming the Red Planet, the indestructible Mars Rover Opportunity has begun exploring the rim of a huge Martian crater and found rocks that hint of ancient hot water and chemicals that haven't been seen in such quantity.

The discovered rock is different from any rock ever seen on Mars, said Steve Squyres, principal investigator for Opportunity at Cornell University.

This rock doesn't look like anything we've ever seen on Mars, Squyres told San Francisco Chronicle. It contains much more zinc and bromine than we've ever seen - clues that we may be dealing with a hydrothermal system here on Mars.
The rover explored a smaller crater named Victoria and climbed down inside that crater's rim only to find layers of ancient sedimentary rock.

Opportunity scientists sent the rover across new terrain to the rim of 14-mile-wide Endeavour crater where they  found a different rock that was interestingly filled with puzzles.

Squyres said the rugged rock is a jumbled fragments of minerals that's been cemented together and thrown up from beneath the planet's surface by a massive impact that happened millions - or perhaps billions - of years ago.

This is like having a brand new landing site for our veteran rover, said Dave Lavery, program executive for NASA's Mars Exploration Rovers.

NASA said the diversity of fragments seen on the rock could be a prelude to other minerals Opportunity might find at Endeavour.