Almost directly after Minecraft wasn't responding, and Chrome wasn't responding, I heard the distinct sound of a skeleton idle sound, and then a couple of parrot sounds, one of which I assumed to be it's hurt sound and the other it's idle sound. It has stopped since I saved and quit from the world and gone to the main menu. It has not come back after loading up the world again. It was day in-game, and there weren't any skeletons around, but there were parrots.