Next to the anthropometries, mostly impressions of naked female bodies, the sponge sculptures are definitely one of the most famous work groups within the oeuvre of Yves Klein. They are monochrome sponges presented on metal steles. The sponge sculptures stimulate the observer’s aesthetic perception in many ways. At first, it is color sensation par excellence, as hundreds of pores enlarge the color surface despite the object’s small appearance. In terms of art history, the sponge sculptures belong to Nouveau Réalisme, which found visual expression by using commodity items. Yves Klein, along with Arman, Daniel Spoerri, Jean Tinguely and others, belonged to the founding fathers of "Nouveaux Réalistes" in 1960. In Klein’s art it is the wonderful sponges that are ennobled from everyday objects to subjects of art.