Ramiel becomes the first Angel to physically penetrate the Geofront when its drill bit breaks through the armor before its downfall during Operation Yashima. Also, since its appearance, other Angels that appeared after it ultimately began to take more aggressive attempts to cause the Third Impact where they began to attack anything that standed in their way instead of ignoring them and only attacking when necessary.
Ramiel is the very first Angel that began to take its aggression on any non-Evangelion beings instead of merely focusing their aggression on Evas alone: While it did share hostilities with any Angel-based entities like Evangelions where it immediately attacked them on sight, Ramiel would also attack other enemies included artillery, tanks, aircraft, etc. that dared to approach it.
Nevertheless, like all Angels, it focused on searching for Lilith, the Second Angel, within the GeoFront to cause the Third Impact.
Ramiel has appearance of a gigantic, floating, crystalline octahedron. The surface of Ramiel's armor is blue and highly reflective. Because of its shape and the manner it moves, Ramiel does not appear to be "alive," in a conventional sense and is too much like floating war machine or UFO of some sort. Contrary to this, the Angel later revealed to be indeed biological: When its remains were demolished later on, bloody red squares were seen where the Angel's armor/surface structure was being taken off, indicating that it does have blood.
This ultimately rectified on its counterpart in Rebuild of Evangelion film series, where it now portrayed as a shape-shifting entity that can change its form to suit its attack or defense requirements, as well as the ability to mold its lower point into a more-organic looking drill rather than the original version, where it appeared as a large, mechanical drill. However, its basic form when not attacking or defending itself is the classic octahedron form seen in the TV series.