The deeper you progress into the cave, the more dangerous the monsters. Mine tracks may give signs such as exclamation marks or skulls that indicate that a big monster is near. White circles that appear above you usually indicate flying monsters. They frequently attack in big groups when in larger areas. When something is out of your light range, it will appear as a white circle as you approach. A white circle that remains stationary is probably a blob. A white circle that begins to move before your light radius touches it may be a monster.