Burrow

From The StarCraft 2 Wiki

Burrowing is an active unit ability that some Zerg units possess or can be upgraded to possess. It is an ability that works very much like cloaking, with the exception that the units cannot move while burrowed. It is still highly useful to be able to hide an entire army on your enemy's doorstep, and attack when the defence force is out.

Navigation - Protoss - Terran - Zerg [e]

Zerg Units (StarCraft II) [e]
(i) = Infested (z) = Zerg-evolution (g) = Swarm Guardian spawn
Ground Units:	Hive Queen | Larva | Drone | Zergling | Baneling (z) | Roach | Hydralisk | Lurker (z) | Nydus Worm | Infestor | Ultralisk
Air Units:	Overlord | Overseer (z) | Mutalisk | Swarm Guardian (z) | Corruptor |
Additional Units:	Broodling (g) | Infested Terran (i) | Infested Protoss (i) | Egg (z) | Lurker egg (z) | Cocoon (z)
Basic Buildings:	Hatchery | Extractor | Creep Tumor | Spawning Pool | Spine Crawler | Roach Den | Baneling Nest | Evolution Chamber | Spore Crawler
Advanced Buildings:	Lair | Hydralisk Den | Deep Warren | Spire | Nydus Network | Hive | Greater Spire | Infestor Pit | Ultralisk Cavern
Cancelled Units:	Shrieker (z)
Cancelled Buildings:	Sunken Colony | Spore Colony | Swarm Clutch

Zerg Units (StarCraft I & Brood War) [e]
(q) = Queen-infested (z) = Zerg-evolution
Ground Units:	Larva | Drone | Zergling | Hydralisk | Lurker | Defiler | Ultralisk
Air Units:	Overlord | Scourge | Mutalisk | Guardian | Devourer | Queen
Additional Units:	Broodling (q) | Infested Terran (q) | Egg (z) | Lurker egg (z) | Cocoon (z)
Basic Buildings:	Hatchery | Extractor | Evolution Chamber | Spawning Pool | Creep Colony | Spore Colony | Sunken Colony | Hydralisk Den
Advanced Buildings:	Lair | Hive | Spire | Greater Spire | Queen's Nest | Nydus Canal | Defiler Mound | Ultralisk Cavern | Infested Command Center (q)
Hero ground units:	Torrasque (ult) | Matriarch (qu) | Infested Kerrigan (it) | Unclean One (def) | Hunter Killer (hyd) | Devouring One (zlng) | Infested Duran (unk)
Hero air units:	Kukulza (mut, grd) | Yggdrasill (ovl)
(ult) = Ultralisk -- (qu) = Queen -- (it) = Infested Terran -- (def) = Defiler -- (hyd) = Hydralisk -- (zlng) = Zergling -- (unk) = Unknown -- (mut) = Mutalisk -- (grd) = Guardian -- (ovl) = Overlord