Displaying -- rand::thread_rng -- using -- println!()

Hello,

The problem :

-- println!("{:?}",rand::thread_rng()); --

The question :

It displays this -- ThreadRng { rng: UnsafeCell { .. } } -- in the cmd, therefore, what would be the meaning of UnsafeCell ? Shouldn't is be displaying random numbers ?

Thanks for the help

Other related question :

Is it possible to write this : -- let secret_number = rand::thread_rng().gen_range(1..=100); --
like this : -- let secret_number = rand::thread_rng(gen_range(1..=100)); -- ?

Thanks and have a good day

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