Complex sentence: This salmon was sometimes called Finntan, or Fintan, in ancient times and was one of the Immortals, and so it was believed that he might be eaten and yet continue to live.
Split into simpler sentences: This salmon was sometimes called Finntan, or Fintan, in ancient times. Stories differ on whether Finntan was a normal fish or one of the Immortals, that could be eaten and yet continue to live.