Narmadeshwar is the stone lingam found on the banks of Narmada, and is believed to automatically have the pran pratishthapan (the deity's life force being called in it), and is therefore, most suitable to be worshipped at home.

A pic of Narmadeshwar at my puja ghar. Narmadeshwar is the stone lingam found on the banks of Narmada, and is believed to automatically have the pran pratishthapan (the deity's life force being called in it), and is therefore, most suitable to be worshipped at home.