Orb Piercers resemble a large porcupine with a head that looks like a mask with multiple holes. They are herbivorous and eat algae that grow in the Flat-creepers, however, they are ferociously temperamental and defensive over their territory.
The Flat-creepers, in the 4th layer, are important passage routes for Delvers, and the Orb Piercer considers the entire 1 km diameter of it to be its territory. Delvers need to be exceedingly cautious and pray for a safe passage when in the area. A single Orb Piercer has taken the limbs and/or lives of over hundred Black Whistle Delvers over the years.
If their life is threatened, it will shed its needles and use them as bait to escape. Their needles have a slow growth rate, so their scarcity might be due to the fact that not many manage to a fully matured state.
They are covered with long, sharpened and venomous needles that can pierce through metal as if was paper, even piercing through the Scaled Umbrella; made from Charcoal Sand and thus a durable Fourth Grade Artifact. While the Orb Piercer's venom is quite slow at killing its victim, it is extremely potent, greatly weakening those affected by it and spreading quickly, which is why many Delvers resort to amputating their limbs.
Orb Piercers are able to instantly unleash a fearsome amount of strength at any given moment, even on wet ground. Their most impressive trait is their ability to sense the force field of the Abyss, which is very uncommon for creatures of the 4th layer. This grants them the ability to sense the flows of consciousness and results in a foresight-like instinct that allows them to predict every movement of other living beings. This makes victory against Orb Piercers in battle almost impossible, and because of their ability to deal fatal wounds to any wildlife, it is said that there no longer exists a creature within the 4th layer that can be called their equal.
Orb Piercers have one major weak point however; the five holes on their face are their force field sensing organ, and they are extremely sensitive spots. If hit or touched there, an Orb Piercer will be thrown into inconceivable pain and a state of confusion that makes it go berserk. However, since it can read one's movements, it is likely that one would never be able to touch it. White Whistle Delvers are likely the only humans capable of defeating one in combat.
- The Orb Piercer was originally called the "Tokajishi" (トカジシ), but because of its habit of messing up treasures (Tama) and lives (Tamashi), Delvers started calling it "Tamaugachi" instead.