NASA scientists say tests on a Mars rock show the planet could have supported primitive life.

The analysis was done by the rover Curiosity, which drilled into the rock, crushed it and tested a tiny sample. The rover was the first spacecraft sent to Mars that could collect a sample from deep inside a rock.

At a briefing at NASA's Washington headquarters on Tuesday, NASA scientist said the rock contains clay minerals that formed in a watery environment _ an environment that may be favorable for microscopic organisms.

Curiosity had already found a hint of the site's watery past _ an ancient streambed that the six-wheel rover crossed to get to the flat bedrock.

The rover made a dramatic landing near the Mars equator last August for a two-year mission.