[en] Optical and radio spectroscopic observations are presented for Malin 1, a galaxy with an extremely low surface brightness disks with an enormous mass of neutral hydrogen, and a low-luminosity Seyfert nucleus. The characteristics of Malin 1 are described and compared with normal disk galaxies. It is suggested that Malin 1 is an unevolving disk galaxy where the surface mass density is so low that the chemical composition and mass fraction in gas change very slowly over Hubble time. The results imply that large and massive H I disks may have formed as early as z = 2 and remained quiescent to the present day. 74 refs