'Martian Features' Found on Earth

In May 2003, the Martian Meteorite ALH84001 displayed signs of microbe-like structures, and underwater mineral and rock deposits. Scientists believed that this rock was a definite key in relaying whether or not the 3.9 billion year old meteorite (and therefore Mars) contained signs of fossil life. The major similarities found on the Mars rock and some rocks found on Earth (in Lake Van) were in the form of pinnacles containing complex carbonates. On Earth, these pinnacles are home to photosynthetic cyanobacteria -- life! These structures are believed to be seen in the rock itself, too. The physical and chemical aspects of the Lake Van structures were a nearly perfect match to the ALH84001 structures. However, much speculation has arisen since the finding of ALH84001, and it is now believed by some that the 'life-forms' found on the Mars rock are just too small to be living organisms at all. This means that physically retrieving rocks from Mars and knowing that they are not contaminated is the best bet for deciding whether or not the structures within the Martian meteorite are remnants of life.

http://news.bbc.co.uk/2/hi/science/nature/3034165.stm