A lenticular galaxy is a type of galaxy which is intermediate between an elliptical galaxy and a spiral galaxy in galaxy morphological classification schemes. Lenticular galaxies are disc galaxies (like spiral galaxies) which have used up or lost most of their interstellar matter and therefore have very little ongoing star formation. They may, however, retain significant dust in their disks. As a result, they consist mainly of aging stars (like elliptical galaxies). Because of their ill-defined spiral arms, if they are inclined face-on it is often difficult to distinguish between them and elliptical galaxies. Despite the morphological differences, lenticular and elliptical galaxies share common properties like spectral features, scaling relations and both can be considered early type galaxies which are passively evolving, at least in the local universe.