The moon was once covered by an ocean of molten rock, data from India's space mission suggests 

 Data from India's recent Chandrayaan-3 mission supports the idea that an ocean of molten rock once covered the moon.  

https://cdn.mos.cms.futurecdn.net/rJsbNwvLLH4QUtNpgTZvdX.jpg

https://www.space.com/moon-ocean-molten-rock-india-space-mission