What is unique about the srtuldbruggs that gulliver meets in laputa?

The struldbrugs that Gulliver encounters in Laputa are unique because they are immortal but age continuously, leading to a state of perpetual decline and misery. Despite their longevity, they suffer from the physical and mental deterioration associated with old age, rendering their immortality a curse rather than a blessing. This paradox highlights themes of the human condition, questioning the desirability of eternal life when it comes with such profound suffering.