The thing is we don't know.Surely the atomic structure if there even is one anymore is way way different than in ordinary conditions.
Actually I could say pretty much anything , like that Julius Caesar lives in one of them because you cannot prove me wrong as you cannot look into one , nor is anyone of those ever achieved here on Earth and studied up close.
The thing is we have theories , and good guesses nothing more on this one.
If you ask me personally , I think there has to be motion , energy cannot just disappear in thin air it has to go somewhere and do something , anything beyond that is poetry.
P.S. Surely the stuff before the event horizon and the radiation that the BH spills as it evaporates is in motion , what is in between I don't know.