"At that point, the shark turned around and settled right below me as if asking for help," Johnson said.
Johnson gently removed the knife without touching the shark's body, and the shark swam away, injured, but knife-free.
"Sharks are an important part of the ecosystem," Johnson later said. "People come to Cayman to see our beautiful reefs... no one expects or wants to see a shark with a knife sticking out of its head."
Nurse sharks are generally believed to be "harmless to humans" unless provoked, according to National Geographic. They're bottom feeders that typically enjoy eating fish, shrimp, and squid, as well as shellfish and coral. Generally they'll only bite or snap at divers if they get stepped on or annoyed, which honestly means they have more in common with you than most surface dwellers you'll meet in your life.