Nostoc is a genus of cyanobacteria found in a variety of environmental niches that forms colonies composed of filaments of moniliform cells in a gelatinous sheath.The name Nostoc was coined by Paracelsus.It derives from the ancient Greek word  nόsos  (νόσος, disease or sickness) .ontaining protein and vitamin C, Nostoc species are cultivated and consumed as a foodstuff, primarily in Asia. The N. flagelliforme and N. commune varieties are consumed in China, Japan and Java, N. commune is also consumed in the Andes.