What structure is found in viruses but not in cells?

Some viruses have genetic material in for of RNA instead of DNA, such thing can be seen in HIV. Viruses have protein coats covered in small molecular receptors/ surface markers.
Viruses like the Bacteriophage have a capsid protein head/shell in which the DNA is held within, a collar and a sheath below it, at the bottom it has a base plate. I can send a picture of a drawing of it to help clarify its structure. Please remember the most important takeaway from this *Viruses are NOT cells nor are they made out of cells* therefore they will not have any molecules that cells naturally already have inside of them except for the genome(DNA or RNA)
also some viruses have envelope/cell membrane. Viral envelopes are pieces of membranes that are taken directly from the host cell/your own cell that made the new virus through. Since Viruses cannot go through mitosis like regular eukaryotic somatic cells(our human cells) do then they have to reproduce by attaching to our host cell, infesting it and then going through either one viral reproduction cycles; Lytic (short cycle)and Lysogenic( long cycle)

If youd like to know more of any of this or have any other questions or want me to include my drawn structure of viruses please dont hesitate to contact me, thank you.

Ithink the answer is nuclear membrane