Phoenix Mars Lander just sent back photos that contain unmistakable
images of the remains of neuroglial cells. The sizes of the cells are
not too large for cells, as Jurassic dinosaurs’ neuroglial cells were
larger than the Martian neuroglial cells as demonstrated in Figure 2
below:

Fig. 1: Labeled are a neuroglial cell, a horizontal and a vertical
blood vessel remains, and a Haversian canal.
http://www.wretch.cc/album/show.php?i=lin440315&b=20&f=o1555128095.jpg&p=5

Fig. 2: Jurassic dinosaur’s neuroglia cell measuring 568 micrometers
in diameter.
http://www.wretch.cc/album/show.php?i=lin440315&b=12&f=o1881223367.jpg&p=57

Fig. 3: Carboniferous human neuroglial cell remains at 515X
http://www.wretch.cc/album/show.php?i=lin440315&b=19&f=1328538642&p=52

Fig. 4: NASA’s original photo
http://phoenix.lpl.arizona.edu/images.php?gID=1114&cID=27
(There are many similar photos, and I forgot which one Fig. 1 came
from.)