Saturn's 'Death Star' moon Mimas may have gotten huge buried ocean from ringed planet's powerful pull 

 The discovery of vast subsurface seas on Saturn's tiny moon Mimas has redefined our view of what an ocean world can be. We may now know how this buried ocean was formed, revealing it is shockingly young. 

https://cdn.mos.cms.futurecdn.net/d24fsa9UAazRNCreEidNHE.png

https://www.space.com/saturn-moon-mimas-buried-ocean-changing-orbit