A type of galaxy with a definite disk of stars and a central bulge, but showing no sign of spiral arms and little or no interstellar material. Lenticulars are classified as S0 galaxies in the Hubble classification. The name comes from their lens-like appearance when viewed edge on. There is very little evidence for current star formation in them. Most nearby galaxies classified as ellipticals are now known to hide rotating discs of stars, making them more similar to lenticular galaxies than the classical picture of a spheroidal elliptical. The main route for galaxy evolution therefore may be from spiral galaxy to lenticular galaxy (possibly via anaemic spirals), with true elliptical galaxies being rare except in the centres of clusters.