Spineling

Spineling, although small, weigh quite a bit. Their steel skin is very hard to break, so the Pokemon have actually been resurrected to the point where they're becoming invasive. The razor on Spineling's back has been believed to be used as a tool by ancient Carahnian peoples, who used the razor for cutting and slicing hard materials. Nobody knows exactly what material Spineling's skin and razor are made of.