Thank you very much westie457 for your swift and helpful reply!
nrg2iso did not work, it returned:
However, iat did work.
It seems that tlod-soe.nrg is already an ISO 9660 image
For anyone who later reads this. Open the Ubuntu Software Center, type in iat and install that package. Then run a terminal, cd to the directory where your .nrg file is.
For my case, the file name was tlod-soe.nrg. So, it was
iat input_file [output_file.iso]
I named the iso file State.
iat tlod-soe.nrg State.iso
Now the archive manager is able to extract the .iso, or I can even mount it. I had also tried Format Junkie, but it didn't properly convert the file.
Thanks once again Westie457