SEATTLE - When Marshawn Lynch was brought to Seattle early in the 2010 season, he was acquired because the Seahawks desperately needed a running back.

What he ended up providing was an attitude and style that became the foundation for bringing the first Super Bowl title to the Pacific Northwest.

And for that, Lynch will forever hold a special place with the Seahawks. He may have been more of a headache off the field than anyone let on during his time in Seattle, but he'll ultimately be lauded as the running back that got the Seahawks to a place they had never been before.

Without saying a word — big surprise — Lynch drew a lot of attention during the fourth quarter of the Super Bowl on Sunday night with a single post on social media. Just a picture, green cleats hanging from a power or telephone line, and a peace sign emoji. It was his way of saying goodbye from football, a decision that his agent Doug Hendrickson confirmed to The Associated Press on Monday saying Lynch intends to retire.

The mercurial running back who enjoyed avoiding media attention away from the field as much as he thrived under the spotlight with the ball in his hands is stepping away just before his 30th birthday.

"Since I've been here he's been the heart and soul, the engine of our offence. A vocal leader. A great influence and one of the best teammates I've ever had," Seattle wide receiver Doug Baldwin said last month of Lynch. "I can't say enough about him."

His final season was an injury-filled disappointment. There were no "Beast Mode" runs in his final season that will forever be in his highlight loop or the image of Lynch leaping into the end zone backward as he did to cap a few great runs in his career. He was a spectator as much as anything, playing in just seven regular season games and one playoff game as injuries were finally a factor in his ability to play.

But as much credit as coach Pete Carroll and general manager John Schneider deserve for what Seattle has become as a perennial power in the NFC, Lynch deserves his share for the demeanour he provided the Seahawks. The moment Lynch arrived, Seattle transformed from being finesse to power. He became the face of the franchise without mounting a campaign to do so. The violence and power with which he ran was Lynch's platform.

Lynch will step aside after nine seasons in the league. Six of those came in Seattle, where he played in the post-season five times. He's second all-time in Seattle history in rushing touchdowns and fourth in yards rushing. He tied for the NFL lead in rushing touchdowns in 2013 and 2014 and is No. 8 all-time in total yards rushing during the post-season. He was an All-Pro, a Pro Bowl selection and perhaps the most revered Seahawks player in the opinion of their fans.

Along with what Lynch provided on the field came his peculiarities when he wasn't carrying the ball. His contract disputes. His avoidance of the media. His memorable performances during two Super Bowl weeks that became as much of a topic as the game itself. And this season, ruling himself out of Seattle's NFC wild-card game at Minnesota just minutes before the team left for the airport.

There was almost certainly going to be a separation between Lynch and the Seahawks after the 2015 season because of financial and evolutionary reasons. Seattle was always going to become Russell Wilson's team moving forward — the nature of a quarterback with a long-term contract agreement — and Wilson's performance this season showed the evolution was in process.

But Lynch's final season should not diminish his meaning to what Seattle has become.

"He's a guy that's been a great leader in terms of his physical nature on the football field and his approach to the game. He has a cool, calming presence out there," Wilson said at the end of the season. "He's one of the greatest running backs to play."