A mysterious radio wave detected on Saturn's largest moon may point to the location of an ocean hidden beneath its surface, the European Space Agency announced.
There's almost an SFnal setting waiting to be used! On the surface of a cold, cold world is a methane solvent biochem based biology. Beneath it is a water based one. Both develop a sapient species. Then...the water guys start to get curious and explore their world above. Hijicks ensue.