In Earth's distant history, when land life was barely achieving a foothold, the dominant life forms were two hard-shelled marine races, the eurypterids and the trilobites. They swam the ancient Silurian seas, happily thinking their simple thoughts and eating anything they could catch, including each other. Some were barely larger than a fingernail (not that there were any fingers around yet). Others were five, even ten feet long. Eventually, humans came along and even later, humans got around to studying fossils. Trilobite and eurypterid fossils weren't particularly common, but they were common enough to become collectable. But then again, humans will collect anything.
In one reality, at a university not to far from Amanda Harp's Bedford, Indiana, there was a vast collection of trilobite and eurypterid fossils. There was one particular fossil that consisted of a well preserved, foot-long eurypterid inside a two foot trilobite fossil. Professors proudly displayed this sample of interspecies digestion. The professors got it wrong.
Ancient eurypterids were a dim bulb, even compared to the newly evolving proto-fish that were just beginning to share the Silurian seas. But this particular eurypterid was moving in a new direction. Sure, the eurypterid had a strong exoskeleton, powerful pinchers, and tireless paddles. But this eurypterid also had a disguise. She had carefully hollowed out a partially-eaten trilobite, crawled inside the trilobite's shell, and therefore had the dubious distinction of being the first creature to invent clothing. The idea caught on, and soon eurypterids were wearing the discarded (or stolen) shells from trilobites, snail-like gastropods, clam-like brachiopods, and even fish scales. Many many millions of years later, a crustacean would independently make the same adaptation, and engender many species of hermit crabs. All good ideas get copied eventually.
In some realities, including mine, our shell-wearing eurypterid eventually became extinct. In others, they fought off the crustaceans, cephalopods, and even fish and exist in the ocean to this day. In at least one reality, they kept getting bigger, stronger, made the transition to land, and in the fullness of time became intelligent.
Consider then Rose the Panzerscorp. Unlike her distant ancestors, (commonly referred to as hermit crabs by some), her shell was specially grown to form just the right shape. Twelve holes here drilled into the six foot oblong, six on the bottom for her motivators, two on each side for her four manipulators, one in the rear for her stinger, and one in front for her face. Although Rose could live outside her shell, doing so was considered the height of vulgarity. Every time she molted, she would need a new shell, and in some cases, a molting Panzerscorp fit so tightly in the old shell that it would have to be cut off.
The shell was made of silica-richened calcium carbonate. Call it limestone, concrete, calcite, or seashell, it is one of the most durable organic or inorganic substances known.
Rose is very fast indeed in the water, and somewhat ponderous but tenacious on the land. She's still small enough that she could climb trees with comparative ease. Strong? So strong it is hard to describe. For one thing, she has to carry around all that calcium carbonate. It's magic.
Panzerscorps could be ferocious fighters, especially once their scorpion-like stinger becomes envenomed. But to their very core, they are patient tricksters who are just as content to wait for food (or adventure) to come to them.