In the beginning, the Invaders were an inorganic substance. Until later, they began to evolve and fuse into human society at a high rate and eventually become organic by the year 2001.
For the Original Invaders (a.k.a. Invader Bosses) and the Invaders in Gate Keepers 21, the crystal actually is the crystallization of their soul. As long as the crystal is not destroyed, the Invaders can always come back to life after a certain period of time. Such as when the Ghost Girl revived Kaiser Kikai and Count Akuma. But when an Invaders "crystal" is completely destroyed the crystal cannot be revived again.
Forms and disguises[edit | edit source]
- Invader Soldier
- Cyclopean Dog
- Six-Engined Jumbo Jet
- ET-11 Ball-Type Invader
- ET-13 Drill-Type Invader
- Twin-Barreled Tank
- "Chef Boyardee"-style Invader
- Highway-Type Invader