Do black holes hide the secrets of their ancestors? 

 Some black holes are so massive they were likely created as smaller black holes that merged. Maybe we can use such black hole "children" to learn about the black hole "ancestors."  

https://cdn.mos.cms.futurecdn.net/J8KEaRxCEJipi9A8TGkwsn.jpg

https://www.space.com/black-holes-ancestors-secrets-space-mysteries