  A Penrose diagram is constructed for a spatially coherent black hole that
smoothly begins an accretion, then excretes symmetrically as measured by a
distant observer, with the initial and final states described by a metric of
Minkowski form. Coordinate curves on the diagram are computationally derived.
Causal relationships between space-time regions are briefly discussed. The life
cycle of the black hole demonstrably leaves asymptotic observers in an
unaltered Minkowski space-time of uniform conformal scale.
