The walkers seen in The Walking Dead: The Ones Who Live episode 5 joined a growing list of Walking Dead zombie types that differ from the standard formula. Though they move slowly like normal zombies, they're significantly harder to kill than most, simply because of the rock-like outer layer protecting their bodies. This makes it understandably difficult to puncture the brain. Similar to the new zombies seen in The Walking Dead season 11 and its spinoffs, the new zombies amounted to an interesting challenge for the show's central protagonists.