Jascoyne the Fish

Then they went into the ship again and it was driven by storms till they saw before them another little island, and the brothers went to land on it but Brendan stopped in the ship. And they put fish in a cauldron and lighted a fire to boil it, and no sooner was the fire hot and the fish beginning to boil, than the island began to quake and to move like a living thing, and there was great fear on the brothers and they went back into the ship leaving the food and the cauldron after them, and they saw what they took to be an island going fast through the sea, and they could notice the fire burning a long way off, that they were astonished. They asked Brendan then did he know what was that great wonder, and Brendan comforted them and he said "It is a great fish, the biggest of the fishes of the world, Jascönye his name is, and he is labouring day and night to put his tail into his mouth, and he cannot do it because of his great bulk."

-- from The Life of St. Brendan , in Lady Gregory, A Book of Saints and Wonders, 1906