Nostoc is an algae categorized in the Cyanophycae, or blue-green algae group. They form gelatin-like bodies that contain filaments called trichomes. The internal components are enclosed by a sheath.
Each trichome is an individual unit within the gelatin body. They form close to the outer sheath of the body, are free-moving and appear as a segmented coil or beads.
Trichomes have a slimy texture and are produced from vegetative reproduction. The cells that make up trichomes produce spores.
The cells don't contain a nucleus but do have chromatin granules, which contain the genetic material.
Heterocyst cells form within the trichome, causing the filament to break and form new colonies. These colonies are small filaments that grow via vegetative reproduction.
Cells within the trichome change into akinetes and form new filaments. The akinetes can survive dry environmental conditions and will start new colonies when water is present.