Dune Shifters are massive beings that live on Methridia. They are not sapient, and are solitary and extremely are. They travel around the planet, slowly looking for other Dune Shifters to mate with. When they move, they cause the sand above them to form a moving dune. If they are above ground, the weight of them makes the sand sink inwards.
The sentient Methrids are their only prey left, and since the growing intelligence and technology of the methrids helps them defend themselves much better than when they were scattered, the Shifters are now slowly being pushed towards demise.