The Narmadeshwar Shivlings are categorized in various types, as per the marking on the stone, which are said to denote the impression of the Gods and Celestial Guardians who worshipped it, mentioned in as Siddhanta Sekhara. However, the Narmada Nadi Shivling is so sacred that you may choose any of them to be worship and it will give the same outcome than any other Narmada Lingam benefits.
Padma or Lotus - The Lotus or Padma mark on Narmada Lingam is said to have been worshipped by Lord Brahma.
Samkhabha Mastaka or Conch Shell - The Shamkhabha Mastaka is the Conch Shell mark on top of the Narmada Lingam which is believed to have been worshipped by Lord Vishnu.
Chatra or Parasol - The Narmada Shiva Lingam that bears the mark of an Umbrella/Parasol, called Chattra (Hindi), depicts that the King of Heaven, Lord Indra worshipped it.
Padha or Three Steps - When a Shivling Narmadeshwar is marked with three steps or Padha, it is said to have been worshipped by Lord Yama, the God of Death.
Siro Yugma or Heads Mark - The Hindu God of Fire, Lord Agni, is said to have worshipped the holy Narmadeshwar Shivling which is marked with the Heads Mark or Siro Yugma.
Kalasha or Water Pot/Vase- If the Kalasha mark is seen on the Narmadeshwar Lingam stone, God of Water or Lord Varuna worshipped the stone.
Dhvaja or Flag/Banner - The Dhavaja or Flag mark on the Shivling from Narmada River, is believed to have been worshipped by God of Air or Lord Vayu.
Gada or Mace - Lord Ishana, who is the keeper of the Northeast direction, as per Vastu Shastra. The mark of Mace or the Gada, on the sacred Narmada Shiva Lingam, signifies that Lord Ishana has worshipped the Lingam