The Gray is a rare Gloople that appears when an Oozle and a Green Gloople combine together. Grays have a silvery body and spikes at the end of it. Despite looking metallic, Grays absorb you much like Oozles. They can turn indestructible when you swing your sword at them. And to top all of that off, they shoot out a lance that will impale you a suck you into it. It has the same health as an Oozle.
Further mutual absorption of the common Gloople seems to lend a progressively more developed and sinister organism. The Gray maintains the advantages of size, but it's additional density and cellular complexity gives it a much harder and still quite mutable outer membrane, which it uses in both a defensive and offensive capacity.
Just as resilient as it's simpler cousin, the Oozle, the Gray gains considerable traits of perception and stimulus response. When directly threatened, the Gray hardens it's outer skin into an almost steel-strong shell that appears to be impenetrable. In this form, while the Gloople is unable of any type of locomotion, any type of attack is ineffective against it. The Gray has also developed this quality into a weapon, by extending a long thread of it's substance and hardening it's tip into this same metallic structure, the Gloople thrusts foward with a lance capable of impaling it's enemies from a distance with deadly accuracy.
The Gray is a very tough enemy to splat with your Splatmaster 3000. A good idea is to use a grenade from the Rewards section in the title screen