New evidence has made it more likely that remnants of Martian microbes were transported to Earth in a meteorite, it was revealed today. A study by scientists from the American space agency Nasa has found chemical signatures in the rock strongly associated with life. The discovery strengthens the case for believing that worm-like structures in the meteorite are 'microfossils' of ancient Martian bugs. Sceptics have pointed out that similar-shaped structures could be formed from non-biological processes. Another unanswered question is whether the microfossils were the result of contamination by Earthly bacteria. This was originally ruled out by Nasa but has...