Complex sentence: Kurma Purana, one of the major eighteen Puranas, a Hindu religious text believed to be written and compiled around century, is believed to have been directly narrated by the Lord Vishnu to the sage Narad, and it contains the details about the Kurma avatar.
Split into simpler sentences: Kurma Purana, one of the major eighteen Puranas, a Hindu religious text. It is believed to have been directly narrated by the Lord Vishnu to the sage Narad, and it contains the details about the Kurma avatar.