 As the main island of stability is thought to lie around 291Cn and 293Cn, undiscovered elements beyond oganesson may be very unstable and undergo alpha decay or spontaneous fission in microseconds or less.The exact region in which half-lives exceed one microsecond is unknown, though various models suggest that isotopes of elements heavier than unbinilium that may be produced in fusion reactions with available targets and projectiles will have half-lives under one microsecond and therefore may not be detected.It is consistently predicted that there will exist regions of stability at "N" = 184 and "N" = 228, and possibly also at "Z" ~ 124 and "N" ~ 198.