Damon Harrison played college football at William Penn University. Don't worry, I haven't heard of it either. It was an NAIA Division II programme, and understandably, it didn't earn him a lot of NFL attention. In fact, he took part in Iowa State's pro-day just to get a little bit more of a spotlight, and to some degree, it worked. Yes, he wasn't picked in the 2012 NFL Draft, but he caught on with the New York Jets as an undrafted free-agent, and from there, things only went up.
An inconsequential rookie year gave way to an open competition at defensive tackle in 2013, and Harrison fought his way -- improbably, but definitively -- to the top of the depth chart.