Species: In dispute
The exponential growth of nanobacterium is indeed the name of a cut by the group "inchoate" off their Sterile album, and it, of course, is available from iTunes (really, this is not a prerequisite for inclusion in the rogues gallery). inchoate seems, alas, to be a band disbanded, or perhaps a disband.
But that isn't what you came here for or what I came here to tell you.
Nannobacteria, or nanobacteria, or nanoballs, or nanobes first came to popular attention when they were found, in 1996, in the famous Martian meteorite, ALH84001. (The first reports of their existence in rocks on Earth go back somewhat before that). Their existence immediately caused controversy, and so it remains. If they are, or were, alive, then there was, and may be, life on Mars. We may have evolved from that life, albeit beginning over a period of more than 3 billion years.
Since then, nanobes have re-emerged periodically in the news and in scientific publications. A 2004 article in the American Journal of Physiology, for example, presented new evidence that they were, indeed, alive - with cell walls and DNA - and may cause a range of human illnesses. They were shown to multiply in sterile filtered extracts, and hence, were not the by-product of microbial activity. Earlier Finnish researchers claimed that they may cause kidney stones... that they build themselves "mineral shell homes" of apatite (a calcareous mineral which is also a component of bones and teeth). Sequential layers of apatite were reported to build up to form the stones. According to Bruce Fouke, a professor of geology and microbiology at the University of Illinois, this overall process is similar to the bacterially mediated formation of coral skeletons or calcareous rocks in hot springs such as those which draw tourists to Yellowstone National Park. The role of bacteria - microbes, not nanobes - is indisputable in that process.
OK, this is certainly exciting new stuff! Where is the controversy? Overall, nanobe's most intriguing and problematic characteristic is their size. Nanobes are an order of magnitude smaller than the smallest microbes, being only 30-200 nm across. The essential problem is that the stuff of life, albeit very small, is not infinitely small. An object of this size would contain only about 100 million atoms, which is not really all that many if you think about concentrations in solution requiring both solute and solvent to be there, or about the number of atoms actually needed to make one protein, or about the very machinery needed to make the protein in the first place. For example, if all of the atoms were used to make water, there would be only 30 million water molecules; at pH 7, only 3 could be dissociated. Moreover, as Kenneth Nealson noted in a letter in Science in 1997, nanobes may simply be too small to contain a single ribosome, and if they do actually have walls and membranes, the available volume shrinks even more - perhaps to nothing.
If not alive, what are they? Jürgen Schieber and Howard Arnot (Geology 31: 717-720, 2003) analyzed the formation of nanobes in vitro and concluded that they were by-products of enzyme-driven tissue decay. As such, the building blocks would have easily passed through the 0.2 µm filters used in other studies.
So I ask again, "does this mean they are not alive?" Or perhaps, we just don't know what it means to be alive? (I once had to deal with a similar question from a young man regarding teenage mutant ninja turtles). If we consider only cinematic possibilities, the rotting tissue hypothesis would clearly never sell. Perhaps that is why nanobes - as organisms or intriguing concepts - remain alive.