Continuing the Who is . . . ? series here on NinerNoise.com, we take a look at the San Francisco 49ers‘ center/guard Marcus Martin, (Check out the earlier articles in this series, about NaVorro Bowman, Blake Bell, DeAndre Smelter, Torrey Smith, Jerome Simpson, and Shareece Wright, Mike Davis and Brandon Thomas, Jarryd Hayne, Alex Boone, Geep Chryst, Tank Carradine, Aaron Lynch, Erik Pears and Tony Jerod-Eddie.