Srimad Bhagvata Mahapurana: Book 11: Chapter 1: Verses 21-24
Some fish swallowed that iron piece, while the particles of the powder were borne by the waves to and deposited on the shore, where they grew into a kind of grass called Eraka.The fish was caught in the net alongwith other fishes in the sea by some fisherman. The iron piece found in its stomach was fixed to the point of his arrow by a hunter. The Lord knew the whole truth and (being almighty) had the power to nullify the curse of the sages; but He did not like to render it ineffectual. (On the other hand) He approved of it, being Himself the Destroyer.