[ck2]

Stephen Hawking theorized it is even possible there is one hiding in our sun.

Below a certain size it would not be detectable by any current method.

And of course there is a PBS Space Time for that

(edit wrong video)

https://www.youtube.com/watch?v=Q6kJaMf3Lgo

(more awesome here https://www.youtube.com/@pbsspacetime/videos )