  Our goal in this work is to better understand the relationship between
replica symmetry breaking, shattering, and metastability. To this end, we study
the static and dynamic behaviour of spherical pure $p$-spin glasses above the
replica symmetry breaking temperature $T_{s}$. In this regime, we find that
there are at least two distinct temperatures related to non-trivial behaviour.
First we prove that there is a regime of temperatures in which the spherical
$p$-spin model exhibits a shattering phase. Our results holds in a regime above
but near $T_s$. We then find that metastable states exist up to an even higher
temperature $T_{BBM}$ as predicted by Barrat--Burioni--M\'ezard which is
expected to be higher than the phase boundary for the shattering phase $T_d
<T_{BBM}$. We develop this work by first developing a
Thouless--Anderson--Palmer decomposition which builds on the work of Subag. We
then present a series of questions and conjectures regarding the sharp phase
boundaries for shattering and slow mixing.
