Ununquadium is a placeholder assigned until the element has been given a final name. Its discovery has been reliably claimed, but remains to be independently verified before a name is officially assigned.It was first detected in 2000. Since then, about 35 atoms of livermorium have been produced, either directly or as a decay product of ununoctium, belonging to the four neighbouring isotopes with masses 290–293. The most stable isotope known is livermorium-293 with a half-life of ~60 ms.