Red bricks contain numerous petrified blood vessels.

The following micrographs show numerous petrified blood vessels that
were found in a ditch carved into a red brick. I found the red brick
on a roadside. It was a small broken piece and heavily weathered. I
washed it and carved ditches into it to expose its fresh surfaces. I
found petrified blood vessels in the carved ditches at many spots. The
following figures show just one such spot.

Fig. 1: shows a broken red brick
http://www.wretch.cc/album/show.php?i=lin440315&b=22&f=1472453637&p=84

Fig. 2: 60X petrified blood vessels in brick
http://www.wretch.cc/album/show.php?i=lin440315&b=22&f=1472453633&p=85

Fig. 3: 200X blood vessel fossil in brick
http://www.wretch.cc/album/show.php?i=lin440315&b=22&f=1472453631&p=86

Fig.4: 1,000X blood vessel fossil in brick
http://www.wretch.cc/album/show.php?i=lin440315&b=22&f=1472453635&p=87