Capillary network—a new biomarker for astrobiology

For recognizing extraterrestrial past life, there are quite a few
biosignatures (biomarkers) in astrobiology (ref.1
http://en.wikipedia.org/wiki/Biosign..._astrobiology). But few of
them are generally accepted and easily verifiable. The author hereby
proposes a new and simple biosignature for astrobiology—structure of
capillary network for extraterrestrial past life. The proposed
biosignature can be easily verified by comparing living animal's
capillary network with similar structures in Earth rocks, meteorites,
moon rocks, Mars rocks, etc.

Capillaries are the smallest blood vessels, measuring 3-15 micrometers
in diameter in humans. Capillaries form network to supply tissues with
blood and exchange gases/nutrients with tissues (ref.2
http://www.sciencephoto.com/media/303632/enlarge).

The structure of capillary network can be a biomarker for the followng
reasons:
Their morphologies are unique in their branching into networks (ref. 3
http://www.visualphotos.com/image/1x3744372/
micrograph_of_capillary_vessels_micrograph_of ,
ref. 4 http://www.wretch.cc/album/show.php?...782889983&p=72
).

Non-biological veins of rocks 3-15 microns across are improbable to
form the kind of branching structures found in capillary networks, as
the crystal habits of minerals are quite regular in their patterns.
Some natural minerals and non-life material do form dendrites, but
their dendrites are too big or too regular or too symmetric to be
capillary network. Two examples:
http://en.wikipedia.org/wiki/Pseudofossil,
http://www.sciencephoto.com/media/216423/enlarge

Fractures (cracks) and fracture fills can mimick capillary networks.
But branching cracks of 3-15 microns across never appear in a large
number in a thin section of rock. If they do, the rock would break at
the cracks and the cracks would not be included in the thin section.
An example of a large number of look-alikes:
http://www.wretch.cc/album/show.php?...044161765&p=13.

Scientists have found that dinosaur blood vessels can be well
preserved (ref. 5 http://www.smithsonianmag.com/scienc.../dinosaur.html
). But no one expects most of the capillary networks to be preserved
intact in rocks. So, it is reasonable to find irregular and
unpredictable patterns of capillaries that survive billions of years.
Such branching, irregular and unpredictable structures are found in
meteorites and moon rocks. Examples:
http://www.wretch.cc/album/show.php?...782874104&p=70

http://www.wretch.cc/album/show.php?...1044145957&p=6

http://www.wretch.cc/album/show.php?...1763&p=10&sp=0

Links to all of my posts: http://www.wretch.cc/blog/lin440315&category_id=0