Zigamoond

One of the many species of large animals crashing too Earth from the moon, Zigamoond is a small (by kaiju standards) predator that hunts in packs of four.
A result of the evolutionary arms race of the Moon's subterranean environment, It's anatomy is strange, with it's eyes located in the nasal slit following the bill, arms tucked into it's chest, a dorsal fin on the pelvis that generates plasma based viruses that flow through the tail and spew from the arrow head tail tip to burn attackers, and the helium sacks throughout it's innards that control it's weight and balance.

Zigamoond's most notable feature however is the saw like lower jaw. This weapon is a fusion of the lower jaw and tongue. The muscles that control the saw are normally relaxed, allowing it to act as a fifth limb and interact with objects, tasting them for any sign of nearby prey. When excited the saw hardens and vibrates subtly. During this, the saw slowly increases in temperature until it reaches extremes. Seconds before biting prey (usually aiming for extremities) the saw vibrates at a high-frequency, allowing it to easily slice through it's prey's flesh and bone.

It's recommended by mech operators to eliminate Zigamoond's from a distance, as metal poses no trouble for their saw jaws.