A Super Soldier.
Meteorillium 317 is a rare metal found in fragments of meteors believed to have originated at the galaxy's core. As described in the Operation Resurrection Project Book, it is used for the improved armor for the Super Soldiers.
Plausibility[]
Meteorillium 317 would actually be hyphenated "Meteorillium-317" under correct format for isotopic notation. Were it to exist, it would have a significantly greater atomic mass number than the heaviest known nuclides today, ununseptium-294 (Uus-294) and ununoctium-294 (Uuo-294). It would most likely have to be placed in a new row of the periodic table, and its electrons would probably extend into the theoretical g block of orbitals.