Chain of decimeter- to meter-wide depressions (indicated by the red arrow) emerged in Ma’at. a) is from an image taken on November 13, 2014; b) is from March 28, 2015. Some boulder-like blocks had become more distinct. Dust deposits around the boulder (indicated by the green arrow) in the upper-left corner of the image(s) may have been excavated, with the boulder isolated at the bottom of the depression. The yellow arrow points to another boulder visible in both images but more clear-cut in the later observation, possibly due to retreat of the surrounding regolith. The observation in (a) was taken at the phase angle of 82◦ with the pixel resolution of 0.62 m. b) was taken at the phase angle of 68◦ with the pixel resolution of 0.5 m (Table A.1).