  We consider an inverse boundary value problem for the heat equation
$\partial_t v = {\rm div}_x\,(\gamma\nabla_x v)$ in $(0,T)\times\Omega$, where
$\Omega$ is a bounded domain of $R^3$, the heat conductivity $\gamma(t,x)$
admits a surface of discontinuity which depends on time and without any spatial
smoothness.
  The reconstruction and, implicitly, uniqueness of the moving inclusion, from
the knowledge of the Dirichlet-to-Neumann operator, is realised by a dynamical
probe method based on the construction of fundamental solutions of the elliptic
operator $-\Delta + \tau^2\cdot$, where $\tau$ is a large real parameter, and a
couple of inequalities relating data and integrals on the inclusion, which are
similar to the elliptic case.
  That these solutions depend not only on the pole of the fundamental solution,
but on the large parameter $\tau$ also, allows the method to work in the very
general situation.
