Now with Hull City, Harper spent over 20 years with Newcastle as a senior player.
"It's remarkable, and very rare, but it's what he wanted to do," Shearer said. "I think everyone respected him for that.
"Even by his own admission, he could have and maybe should have moved on. I think he had opportunities from some big clubs.
"But he loved Newcastle, and wanted to stay and play. There were big barriers at time, and in particular Shay Given. He's a top-class goalkeeper."
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