Danny Pine was known to have this ability.

Metallic Exoskeleton is the biological ability of a DNA Alternate to produce metal in the pores of the epidermal layer that spreads to encompass the body in a flexible, organic metal shell. This shell is theoretically shed when the increase in adrenal activity subsides and the sudden rush of adrenaline that brought the shell about ceases.

The metallic exoskeleton is of a previously unknown element that seems partially organic. The element is extremely durable, exceeding both steel and titanium. The element is flexible enough that normal movement is not hampered. The exoskeleton allows for drastically increased physical strength, while also causing the Alternate to become significantly heavier.