Complex sentence: Lines of Zahn are thrombi that when formed in the heart or aorta have visible and microscopic laminations produced by alternating pale layers of platelets mixed with fibrin and darker layer containing red blood cells.
Split into simpler sentences: Lines of Zahn are a characteristic of thrombi that appear when formed in the heart or aorta. They have visible and microscopic laminations produced by alternating pale layers of platelets mixed with fibrin and darker layer containing red blood cells.