Navicula is a genus of boat-shaped diatom algae, comprising over 1,200 species. Navicula is Latin for 'small ship', and also a term in English for a boat-shaped incense-holder. Diatoms — eukaryotic, primarily aquatic, single-celled photosynthetic organisms — play an important role in global ecology, producing about a quarter of all the oxygen within Earth's biosphere, often serving as foundational organisms, or keystone species in the food chain of many environments where they provide a staple for the diets of many aquatic species. Navicula diatoms are known for their ability to creep about on each other and on hard surfaces such as microscope slides. It is thought that around the outside of the navicula's shell is a girdle of protoplasm that can flow and thus act as a tank track. 'Navicula'. World Register of Marine Species.