When Doctor Phlox was studying epithelial cells from a Xindi pilot he found the pigmentation far more colorful than expected and later identified the cells as scales. (ENT: "The Xindi") Harry Mudd's complexion was "fair", according to his police record. (TOS: "Mudd's Women" ) In 2368, while preparing to alter Data's appearance to that of a Romulan, Doctor Beverly Crusher noted that changing his skin pigmentation shouldn't be too difficult, while changing it back might be. (TNG: "Unification I" )