(CNN) NASA's Mars rover Curiosity made a valuable discovery.
The two-thousand-pound super-rover found stones in conglomerate rock that suggest water was present on Mars in the past.
What represents the consensus opinion of the science team that this is a rock that was formed in the presence of water, characterized as being a vigorous flow on the surface of Mars.
Scientists say the gravels seem too large to have been transported by wind -- so they likely were in a stream bed.
They believe water and sediment flowed down the crater where the rocks were found.