Lipofuscin is a brownish pigment left over from the breakdown and absorption of damaged blood cells.
Lipofuscin is found in heart muscle and smooth muscles and is also called the aging pigment.
Kumar V, Abbas AK, Aster JC. Cellular responses to stress and toxic insults: Adaptation, injury, and death. In: Kumar V, Abbas AK, Aster JC, eds. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Philadelphia, PA: Elsevier Saunders; 2015:chap 2.