Muir spent his early years learning American football with the Sutherland Seahawks Gridiron Club in Sydney. Muir has evolved at left guard in two seasons at Baylor. The 6-foot-6, 315-pound lineman earned first-team All-Big-12 honors as a senior.
One of Muir's main jobs will be using his massive body to create holes in opposing defensive lines for Hayne and the other 49ers running backs to slip through.
Muir, who like most of Australia's latest crop of NFL players grew up playing Aussie rules, also had a year at Hawaii. His brother, Sean, is also an offensive lineman at Baylor.