The Earthen Allied Race mount has been discovered in The War Within Alpha datamining — take a look at the Slatestone Ramolith, a mossy stone ram!
Slatestone Ramolith Proto Ram Earthen (Grey Skin, Grand Horns, Gold Saddle)Slatestone Ramolith Description: Earthen ranchers talk often of this creature's resilience and how the rain ricochets off of its lustrous coat.
Source: Achievement: Allied Races: Earthen Model id: 117965 Based off datamined item sources, players will be able to earn this mount by completing the achievement for recruiting the Earthen as an Allied Race, similarly to previous Allied Race mounts such as the Nightborne Manasaber and the Kul Tiran Charger.