LONDON, Ontario -- Joe Thornton and Logan Couture have been San Jose Sharks teammates for 10 NHL seasons. After all that time, Couture said it's hard for him to imagine not having Thornton around.

"He has the invaluable assets that you need in any dressing room. When he walks in, he demands respect, he creates a fun atmosphere and fun environment, I couldn't imagine playing on a team without Jumbo," Couture told NHL.com on Thursday. "My mind just can't work that out, not having Joe around, because it's been 10 years with him and it's been so much fun."

Thornton, who had 51 points (16 goals, 35 assists) in 73 games last season, remains an unrestricted free agent but Couture said he is confident the 40-year-old forward will return to the Sharks based on a summertime conversation.

"I talked to Joe a month ago and asked him what was going on and he said, 'Oh don't worry about it,' so I took that as he'll be back," Couture said. "I just kind of figure it's going to happen, he's still got time, I'm sure he'll be back with the Sharks."

San Jose does not have a captain after forward Joe Pavelski signed with the Dallas Stars as an unrestricted free agent following 13 seasons with the Sharks. Couture, who has been mentioned as a candidate to replace Pavelski as captain, said Thornton is at the forefront of the culture that has been created by the way he carries himself.

"The word culture is used a ton, but he sets the tone for that," said Couture, who held his third annual charity casino event, All-in For Brain Research. "Everyone is allowed to be themselves, he's himself, Brent Burns is himself, Evander Kane is himself, everyone is different, but Jumbo starts that, and then there is accountability. You still need to be a professional and play the right way and he'll let you know if you aren't."

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When forward Kevin Labanc opted to sign a one-year, $1 million contract on July 8 as a restricted free agent despite tying Kane for sixth on the Sharks with 56 points (17 goals, 39 assists). Couture said it was another example of what Thornton helped to create.

"With [Joe] years ago, he could have left San Jose multiple times and taken way more money but he didn't, he wanted to take his term for the team and wanted the team to do well and be able to sign more guys," Couture said. "That filters down from top to bottom. When you're signing your deal, that's one of those things in the back of your mind, that if Joe Thornton does that for this team, then I should do it as well."

Thornton has been working out at the Sharks practice facility, and Couture said knowing Thornton, he just cannot see him stepping away from the game right now given he's training this far into the offseason.

"He can't give it up, he works so hard, so the day he stops I'll be shocked," Couture said. "When we lost to [the St. Louis Blues in the Western Conference Final], I ran into him in the gym like nine days later and Jumbo had already been in there working out, and that was not his first day back. He loves the game, loves it, more than anyone."

Couture, who had 70 points (27 goals, 43 assists) in 81 games last season, is not alone in recognizing Thornton's determination to return. Timo Meier echoed that sentiment when asked about Thornton at the NHL European Player Media Tour on Thursday.

"I think everybody that knows Jumbo expects him to be back," Meier said. "The way he's training and the way he's still in shape with his 40 years, I don't doubt that he's coming back. He'll be playing until he can't anymore. Probably he'll play longer than he can walk. I really hope he's going to be back because he's just a huge presence and the guys all love him there and obviously we all know what kind of hockey player he is."

Thornton in June suggested he intends to return for a 22nd NHL season and added he believes he could play up to five more seasons. Couture would not guarantee that but said he would not be surprised if he did.

"I could see it, that would put him to 45, but with his passion and love for the game, I could see it," Couture said.