User blog comment:Mckrongs/Rust Duramboros Discussion/@comment-3133156-20111022150546/@comment-1431853-20111022221553

I'm with AWc here. The reason young Dobo would lack the moss is because it has not had time to grow yet. Adult Dobo's time spend in the forest would allow the moss time to grow, but the desert Dobo would not have exposure to the conditions that would allow the moss to grow. Also, the desert Dobo's skin would be lighter because living in the desert would cause light desert sand to pack up against its skin.

..At least that's my theory.