Carbon is the fourth most abundant element by mass in the universe after hydrogen, helium and oxygen. As the term 'allotropy' suggests, carbon displays a multiplicity of modes of existence. This chapter explores their coming into being in relation with human history. It tells many stories, ranging from legends about mephitic air and the key role of carbon in building the periodic table to the story of the carbon skeleton as a backbone of life and pillar of chemical industry. The chapter also emphasizes the ways in which each persona of carbon interacting with our material and symbolic practices create togetherness and sketch the lines of our common world. In surveying the multiple identities of carbon, the chapter highlights three major features of technoscientific objects. The unbounded productivity of technoscientific objects may be due to their multiple identities, 'carbon' can be considered as the 'orthonym' of a multiplicity of heteronyms, an ontography seems more appropriate than an ontology for carbon.