Magnesium is an essential constituent of animal and plant tissue, making it an ideal choice for cybernetic alloys. Alloyed forms of magnesium have considerable tensile strength. Alloyed with aluminum or copper, it is used extensively in spacecraft parts and cargo bays, cybernetic limbs, and optical refinement devices. The unalloyed metal is used in flash grenade powders, incendiary deoxidation bombs, and signal flares.