  We solve the persistent problem of the structure of the lowest $1/2^+$
resonance in $^9$Be which is important to bridge the A=8 gap in nucleosynthesis
in stars. We show that the state is a genuine three-body resonance even though
it decays entirely into neutron-$^8$Be relative s-waves. The necessary barrier
is created by "dynamical" evolution of the wave function as the short-distance
$\alpha$-$^5$He structure is changed into the large-distance n-$^8$Be
structure. This decay mechanism leads to a width about two times smaller than
table values. The previous interpretations as a virtual state or a two-body
resonance are incorrect. The isobaric analog 1/2$^+$ state in $^9$B is found to
have energy and width in the vicinity of 2.0 MeV and 1.5 MeV, respectively. We
also predict another 1/2$^+$ resonance in $^9$B with similar energy and width.
