Drill Core (IMAGE) Woods Hole Oceanographic Institution Caption These remarkable rocks, recovered by the Ocean Drilling Program (ODP) on board the drilling vessel JOIDES Resolution, are from the Earth's upper mantle that underwent intense alteration by heated seawater. The rocks show a systematic change in color from rusty brown (top) to green and black (bottom), reflecting the chemical gradients across the fluid mixing zone. These chemical gradients played a key role in supporting microbes with chemical energy and the substrates they needed to thrive. Fossilized microbes were found in white veins consisting of the minerals calcite and brucite. Credit Photo courtesy of Ocean Drilling Program Usage Restrictions To accompany news stories related to this research and with proper credit. License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.