Mammothmon was revived from ancient times and continuously battled Virus Digimon, causing its whole body to become consumed by viruses and leaving it as an Undead Digimon composed of nothing but bones. After dying, SkullMammothmon’s survival instinct as a Vaccine type has only grown stronger, and in order to keep fighting, it has lost all emotion or intellect that do not aid in exterminating viruses. As long as the DigiCore shining in its chest remains unharmed, it can maintain vital activity even as a skeleton. But the moment this exposed DigiCore is attacked spells the end for SkullMammothmon. It uses its special move Spiral Bone to hurl vertebrae spun at high speeds.
