Parked in a clearing were Covenant vehicles, lined in three rows of four: mortar tanks. The tanks had two wide lateral fins, beneath which were armored anti-grav pods. They were extremely stable and fired one of the Covenant’s most powerful ground weapons: the energy mortar. Fred had seen them in action; they fired a shaped blast of plasma that obliterated everything within twenty meters of impact. Titanium battle plate, concrete, or flesh—it all vaporized.
    Marines called these tanks “Wraiths” because you usually got one look at them before they made you one.
	...
	In unison the Spartans turned and fired at the far corner of the formation of tanks. Two blue-white blobs of liquid sun spat from the Wraiths and detonated. There was a dazzling light, an expansion of superheated white fire—and then there was glass-smooth ground and the smoldering skeletons of seven Wraith tanks.
	More luck. If the tanks had been active, with hatches secured, they might have survived the first volley.

Halo: The Flood Ch 12