This micrograph is marked for indisputable Martian blood vessel
remains found in meteorite NWA 2986, which, according to NASA,
originated from Mars:
http://www.wretch.cc/album/show.php?i=lin440315&b=29&f=1782820145&p=62

The micrograph shows blood vessel remains that tapered, branched,
curved, contained red blood cells, and appears raised from the matrix.
No mineral fibers, geological fractures or bioturbation burrows
resemble those Martian blood vessel remains.

Image source: 11th photo in NWA 2986 micrographs at
http://www.meteorite.com/meteorite-gallery/meteorites-alpha_frame.htm

More indisputable blood vessel remains in meteorites:
http://www.wretch.cc/blog/lin440315/21596575

http://www.wretch.cc/blog/lin440315/21597946