Megium

Megium was the heaviest element ever, it was synthetic and had a radioactivity of over 1700 isorems.

Megium was not at all what Federation chemist had predicted ever since the Island of stability was increased by 23% in 2397. Megium was finalized to be heaviest artificially and naturally formed element in the [known] universe.

Megium was extremely mysterious, no one knowing more then it's atomic structure, number mass, theoretically bonds, and one theoretical isotope (563Megium).