If you read just the headline from this Telegraph article, you might think it's the biggest scientific discovery of all time:
Mars rover finds signs of microbial life
Wow! But if you read the actual article, you might be a tad bit disappointed:
Nasa says its Mars rover Spirit has discovered "the best evidence yet" of a past habitable environment on the planet's surface. Spirit has been exploring a plateau called Home Plate, where it discovered silica-rich soil in May. Researchers are now trying to determine what produced the patch of nearly pure silica - the main ingredient of window glass. They believe the deposits came from an ancient hot-spring environment or an environment called a fumarole, in which acidic steam rises through cracks. On Earth, both of these types of settings teem with microbial life, said rover chief scientist Steve Squyres.
Yes, on Earth we find lots of bugs in such places. But fumaroles would exist without life, and if we find them on Mars that doesn't mean we've actually uncovered signs of life. For that, we'd actually have to find some, y'know, signs of life. Duh.
