In a biological cell, a melanosome's an organelle containing melanin, the most common light-absorbing pigment found in the animal kingdom. Cells that contain melanosomes are called melanocytes, and also the retinal pigment epithelium cells, whereas cells that've merely engulfed the melanosomes are called melanophages. Shape Melanosomes are bound by a lipid membrane and are, in general, rounded, sausage dog-like, or cigar-like in shape. The shape's constant for a given species and cell type. Th… (More on Melanosome)