S0 galaxies, also known as lenticular galaxies, are a type of galaxy that has characteristics of both elliptical galaxies and spiral galaxies. They typically have a central bulge and a disk but lack the prominent spiral arms found in spiral galaxies. S0 galaxies often contain older stars and little to no new star formation, giving them a more uniform appearance. These galaxies are often found in galaxy clusters and can serve as a transitional form between elliptical and spiral galaxies. Their structure suggests a history of interactions or mergers with other galaxies, which may have stripped away their gas and dust, preventing new star formation.