usually summoned by arachnos flier, they are sometimes found underground in grandville
++++FREEDOM+++++
Funeral Thirst lvl50 claws/SR stalker
Blood of the Blade lvl50 katana/regen scrapper
Stone of the Earth lvl50 stone/stone tank
Catalepsy lvl50 SS/Invul Brute
Despised-Icon lvl50 dark/dark defender
Hope Conspiracy lvl28 Ice/Kin Corruptor
yeah, my first time in those tunnels on a low lvl stalker was interesting when those popped me
Liberty
My 50s:
Hero: Armor Assassin (scrapper), Cross Dresser (scrapper), Surly Seaman (blaster), Defensive End (Tank), Rad Rhino (Cont)
Villain: Beast Infection (Corr), Sweet Zombie Jesus (MM), Milk Weasel (Stalker), Orgullo (MM), Agent Eris (Crab)
If you ever done the STF you are familiar with those. They usually sneak up on you while you are destoying the buff towers 
Paragonian Knights
Justice Company
As I vaguely recall, in the early days of the Arachnos Flier, it would generally spawn far out of place below the Grandville map due to a bug, which was very annoying for all the badge hunters because it was almost always unfindable. When under the map, the Flier would aggro on people walking through the tunnels. It couldn't shoot them, but it could spawn cruise missles in the tunnels.
Generally, if you see a cruise missle in the tunnels, it generally suggests that the Arachnos Flier spawn bug occurred, and you should probably /bug it. (And probably ask that this thread be moved to a different forum.)
Lol whut? Ever seen these things before? The only place I've found em are in the tunnels leading towards the Fab in GV. They self destruct on you for a decent chunk of our health.