Grimlock keeps a collection of the parts he's torn off his Decepticon enemies. His super-thick ultramantium skin in both robot and dinosaur mode is coated in energy-absorbing materials, making him nearly impervious to damage. There are many who might say much the same thing about his mind. He is acutally quite smart, but a programming flaw in his speech cneters gives him only the most basic communications skills. He dislikes the weak, but is dedicated to the protection of those he views as lesser creatures. The only thing he hates more than weakness, in fact, is those who exploit the weak.