Nanobes are bizarre filamentary structures found in some rocks. They range in size from 20 nanometers to about 50 nm, around 10 times smaller than the smallest known bacteria. They are similar in size to some of the smallest known viruses, such as Parvovirus, only 25 nm across and with a genome only 5,000 base pairs long.
Some theorize that nanobes are living organisms that self-replicate and even assist with the calcification of teeth, but the jury is still out on that hypothesis. Nanobes must not be confused with nanobacteria, another type of super-small controversial possible class of life. The difference is that nanobacteria are said to have cell walls, whereas nanobes are wall-less filamentary structures. If nanobes are confirmed to have genetic material, as one researcher has claimed to have found, they could be the smallest and simplest class of life ever discovered, and maybe even among the first organisms on Earth.
Many scientists are skeptical that nanobes are living because estimates of the minimum possible size for an organism range around 200 nm. Plasmids and DNA require structures of at least this size to perform the functions common to all life as we know it. Therefore, if nanobes are living, they may reproduce using a heretofore unknown form of self-copying. Imaging with an electron microscope has found that they have morphologies somewhat similar to fungi. Their extremely small size makes them resistant to testing and analysis.
Nanobes are sometimes compared to prions, a small protein-based life form responsible for diseases such as bovine spongiform encephaly (BSE), which was considered controversial when it was first proposed in 1982.
It has been claimed that nanobes may have been found on the Martian meteorite ALH84001, along with nanobacteria, but unfortunately for nanobe enthusiasts, this is evidence against their life-status, not in favor of it. There are many mineral structures that may superficially resemble life forms, but these are built from the self-assembly of molecular structures, not evolution and natural selection. If nanobes were living, it is likely we would observe more variation in both their structure and the frequency with which they are located in samplse.
