Brahma is a secondary creator as described in the Mahabharata and Puranas, and among the most studied and described. Born from a lotus emerging from the navel of Vishnu, Brahma creates all the forms in the universe, but not the primordial universe itself. In contrast, the Shiva-focussed Puranas describe Brahma and Vishnu to have been created by Ardhanarishvara, that is half Shiva and half Parvati; or alternatively, Brahma was born from Rudra, or Vishnu, Shiva and Brahma creating each other cyclically in different aeons (kalpa). Thus in most Puranic texts, Brahma's creative activity depends on the presence and power of a higher god.