The living entity can live merely by his own power, without the help of skin, marrow, bone, blood and so on, because it is said, asango’yam purusah–the living entity has nothing to do with the material covering. Hiranyakasipu performed a severe type of tapasya, austerity, for many long years. Indeed, it is said that he performed the tapasya for one hundred heavenly years. Since one day of the demigods equals six of our months, certainly this was a very long time. By nature’s own way, his body had been almost consumed by earthworms, ants and other parasites, and therefore even Brahma was at first unable to see him. Later, however, Brahma could ascertain where Hiranyakasipu was, and Brahma was struck with wonder to see Hiranyakasipu’s extraordinary power to execute tapasya. Anyone would conclude that Hiranyakasipu was dead because his body was covered in so many ways, but Lord Brahma, the supreme living being in this universe, could understand that Hiranyakasipu was alive but covered by material elements.
Source: A.C. Bhaktivedanta Swami Prabhupada (2014 edition), “Srimad Bhagavatam”, Seventh Canto, Chapter 03 – Text 15 & 16