Zhang Heng got rid of human-frogfish monster with the knife. After that, he checked his diving equipment, especially the oxygen cylinder, and confirmed that it was not damaged when the monster threw him around earlier. After all these were completed, Zhang Heng gestured to Nellie and asked if she was fine.
Nellie was a little confused, but she could not ask all those questions underwater. However, she did feel good to meet her partner again. If it were not for Zhang Heng's interference, Nellie believed she would've died or ended up like one of those pearl divers where they were snatched by those hideous and terrifying monsters.