Ireul is a nano-scale entity, similar to a virus. In addition to its A.T. Field, it demonstrates an ability to adapt and evolve to almost anything. Rather than "moving" in the conventional sense, the angel seems to simply spread by rapidly reproducing at the cellular level. It is not known whether or not Ireul has a core. It appears in the Pribnow Box deep in the GeoFront, where it is initially mistaken for corrosion before spreading to where the pilots are taking part in test.