User blog comment:Lord Loss/Monster Hunter Theory... Blog/@comment-6050823-20140511185735

Well, I don't knew if you guys knew this about the Great Desert but it was once at the bottom of the sea/sea floor in ancient times. The evidence that proves this is ancient coral, shells, and some fossilized organisms buried under layers of sand. Jhen Mohran has been suggested to possibly eat these.

From this many fans believe that the same could also go for the some of the other Deserts.