Unknown; has been referred to as both male and female
A rubber jelly dolphin
The Shell-Shocked Cat is an intelligent cat that, regrettably, developed shell-shock somehow.
When Kakamu was fighting Tahar'ok and Kulnak some time ago, it came out of a portal covered head to paw in potato peelings, and slapped Kakamu round the face with a large blue jelly dolphin nine times before transforming into its alternate form, a very aged cheddar.
A short while later, when Tratus was at the Mata Nui II firing at Ricochet in his stolen ship, the Shell-Shocked Cat decided to deal with him. Tratus was subjected to the same fate... being beaten repeatedly with the Jelly Dolphin of Doom.
Eventually, the Shell-Shocked Cat decided to retire from its life of crime and work in the McYonalds restaurant based in the Stouttish Islands as a cook. Several years later, when BONES, his Ayy-Lmaliums, and Pumkin arrived in the restaurant looking for soldiers, the Shell-Shocked Cat tore off its uniform, grabbed its jelly dolphin, and signed up.