On March 21, 2006, Jack Dorsey posted the world's first tweet: "just setting up my twttr." Dorsey was named the company's chief executive officer. He removed his nose ring in an attempt to look the part of a mature Silicon Valley executive, though he kept his boyish, mop-like haircut and abstract, forearm-length tattoo whose shape represented, among other things, the human clavicle bone. Co-founder Evan Williams replaced Dorsey as Twitter's CEO in October 2008, with Dorsey staying on as company chairman.