Human blood cells include 94.2% red blood cells, 0.13% white blood
cells and 5.65% platelets. The following figures show white blood cell
remains alongside red blood cells in coal and Martian meteorite
NWA998.

Figure 1: shows one white blood cell (monocyte) found in anthracite
coal of the Carboniferous Period
http://www.wretch.cc/album/show.php?i=lin440315&b=27&f=1610635979&p=16

Figure 2: shows two white blood cells (neutrophil & monocyte) found in
Martian meteorite NWA 998
http://www.wretch.cc/album/show.php?i=lin440315&b=28&f=1177205523&p=208

Source and credit for Figure 2: http://www.meteorite.com/meteorite-gallery/meteorites-alpha_frame.htm
(Select NWA998-1600X)