Hopefully the question wasn't misunderstood, but the answer is Iron and Nickel, which I made three60 choose between his three, so he's up. We ended up finding out that the fused Nickel quickly (on the order of 80 days) decays into Cobalt, which similarly quickly decays into Iron. Cobalt, though between Iron and Nickel on the periodic table, is not created via fusion directly. Thus generally anything heavier than Iron is going to be created via supernovae, which is due to the fact that you need to add energy in order to bind the particles needed to create those heavier elements.