from The American Heritage® Dictionary of the English Language, 5th Edition.
- noun A fossil, as of a pollen grain or unicellular organism, that is too small to study with the naked eye.
from Wiktionary, Creative Commons Attribution/Share-Alike License.
- noun any
microscopic fossil, such as that of a pollen grain
from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
- noun a fossil that must be studied microscopically
Sorry, no etymologies found.
Then he puts up an image of a microfossil from the Murchison meteorite and it looks quite like the first, including the presence of trichomes or strands of cells in sheaths, and later he shows images from Murchison very similar to those stacks of dimes.
Microbes can flash fossilize and presto, you can have a microfossil that registers as extraterrestrial when it was alive on Earth not that long before.
Nonetheless, in the time since the paper first came out to such acclaim and criticism, many living organisms as small as the reported Allan Hills microfossil have been identified and categorized on Earth.
So how do McKay and others determine whether a microfossil is from beyond Earth or is simply terrestrial contamination?
McKay did report the possibility that the meteorite contained a Martian “microfossil”—the minute remains of the outer sheath of a bacterium—but his strongest results involved the presence of minerals and rock alternations that are considered signs that bacteria and other microbes were once at work eating the rock, transforming the rock, and depositing waste in the rock.
“Raman imaging spectroscopy of a purported 3.5 billion year old microfossil” abstract.
Steve's microfossil search achieved success: he found a fossil ostracod!
Fortunately we have completed all of the suit study trials, have collected a bunch of rock samples for the microfossil and extremophile studies, and have finished work on the telescope, so we are in good shape, but there's still plenty of data analysis to do on those projects and lots of GPS tracking and geotagging yet to do.
McKay no longer argues as strenuously that the tiny microfossil is an important part of his case, because he is finding what he believes are much larger Martian microbes in other meteorites.
Not surprisingly, “proof of life on Mars” is the way the story played when it came out with a bang in 1996, and the “microfossil” was the star of the show.