Thornton has been skating at the Sharks practice facility in San Jose, where he was photographed with former teammates Patrick Marleau and Christian Ehrhoff on Monday.
Ehrhoff, a defenseman who retired on March 26, 2018, was wearing a black T-shirt and shorts and stood between Thornton, who was in his Sharks practice jersey, and Marleau, who was wearing a Toronto Maple Leafs practice jersey.
Marleau, also an unrestricted free agent after being bought out by the Carolina Hurricanes five days following a trade from the Maple Leafs on June 22, could be interested in signing with the Sharks. Marleau, who turns 40 on Sept. 15, played 19 seasons in San Jose before signing with Toronto on July 2, 2017, and is the Sharks' all-time leader in games (1,493), goals (508) and points (1,082).
Meier said he doesn't have a feel for Marleau's situation because the 22-year-old has been living in Switzerland during the offseason.
"I probably know less than you do," Meier said. "I've been trying to do my work, trying to get in shape for the season and obviously enjoy my time at home, prepare the right way for the season."