  We discuss quantum dynamics in the transverse field Ising model in two
spatial dimensions. We show that, up to a prethermal timescale, which we
quantify, the Hilbert space 'shatters' into dynamically disconnected
subsectors. We identify this shattering as originating from the interplay of a
$\mathrm{U}(1)$ conservation law and a one-form $\mathbb{Z}_2$ constraint. We
show that the number of dynamically disconnected sectors is exponential in
system volume, and includes a subspace exponential in system volume within
which the dynamics is exactly localized, even in the absence of quenched
disorder. Depending on the emergent sector in which we work, the shattering can
be weak (such that typical initial conditions thermalize with respect to their
emergent symmetry sector), or strong (such that typical initial conditions
exhibit localized dynamics). We present analytical and numerical evidence that
a first order-like 'freezing transition' between weak and strong shattering
occurs as a function of the symmetry sector, in a non-standard thermodynamic
limit. We further numerically show that on the 'weak' (melted) side of the
transition domain wall dynamics follows ordinary diffusion.
