(a) RGB colour composite of Phobos from HiRISE image PSP_007769_9010, adapted from Basilevsky et al. (2014). Black labels indicate the approximate positions of the B1, B2, cr, and LIMTOC ROIs. Red and blue drawings indicate craters excavating Red and Blue unit materials, respectively. White lines indicate the approximate extent of the Blue unit and of Stickney floor (Basilevsky et al. 2014). Insets show close-ups of the cr ROI crater (b), visible ejecta of fresh craters (c), and the Limtoc crater and part of Stickney floor (d). Arrows indicate fresh crater ejecta.