Photographs taken by the European Space Agency's Mars Express spacecraft seem to indicate that there still could be active volcanism on the Red Planet. The spacecraft took detailed observations of five Martian volcanoes, and found that some had erupted as recently as 4 million years ago. Although this is ancient in human terms, it means that Mars is still probably geologically active. This is very important to biologists, because it means that there could be geothermic vents with heat and liquid water - havens for microbial life.