The Beetles stay immobile, curled-up in a ball when there's light. They are invulnerable but won't do any harm while in this state. However, when light goes out after nearby candles are destroyed), they will start to move around.
Arthroverta appears at the Monastery as the game's first boss. Its appearance is that of a giant beetle-like monster with a human-like face hiding inside the carapace located on the upper part of its head. Its attacks are predictable and has relatively low health compared to later bosses.
It has three attacks:
It can curl into a ball and try to ram the player down.
It opens the carapace on top of its head and a human-like face spits a web in midair which arcs down on the player (on Hard Mode, Arthroverta fires several webs at once in a continuous stream).
It tries to use its claws to smash the player.
The last two attacks are used alternately. The Arthro Medal (gained for defeating Arthroverta without receiving a single hit), hails it as the "Earth Beetle". There's no reward for defeating Arthroverta other than its medal, but inside the next room you'll watch a cutscene which unlocks Wygol Village.