Aiyangar states that the following verse from the Taittiriya Aranyaka (p"rapāṭhaka" 1.23-25) 'is narrated in connection with the ritual called "Arunaketuka-kayana", in which the tortoise ['Kurma'] is placed below the "uttara-vedi" [altar].In it Prajapati or his juice the Tortoise is called "Arunaketu" (one who had red rays)'