NATURE can trick researchers into thinking they see fossils of miniature
bacteria, warns the geologist who coined the term 鈥渘annobacteria鈥� for such
organisms.
Before the hype of the Martian meteorite ALH84001, Robert Folk from the
University of Texas at Austin reported finding tiny rods and spheres that
resembled dwarf bacteria in samples from hot springs. The structures were much
smaller than any other organism but prompted speculation that blobs in
meteorites were evidence of life. But now Folk and his colleagues have formed
similar structures from sterile calcite (Geology, vol 27, p 347).
The experiments show that inorganic crystals and fragments of larger bacteria
can mimic the telltale rods and spheres. But Folk remains convinced that the
miniature bacteria are out there. 鈥淗e鈥檚 not backing off an inch,鈥� says colleague
Brenda Kirkland.
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