Blizzard updated the Wrath of the Lich King Bestiary page with the new unit: The Jormungar.

Jormungar
The fiercely aggressive jormungar are a marvel of evolution, possessing rows of chisel-like teeth capable of boring through solid rock, as well as muscular, flattened bodies well adapted to rapid underground navigation.

Legends tell of the nerubians’ using the jormungar as creatures of labor, forcing them to carve massive tunnels through Northrend’s subterranean ice and lay the groundwork for the nerubians’ ancient civilization. With the fall of the nerubian empire, swarms of rogue jormungar ran amok, drilling through the region’s permafrost, attacking surface dwellers, and devouring everything in their path.