  During a binary black hole merger, multiple intermediary marginally outer
trapped tubes connect the initial pair of apparent horizons with the final
(single) apparent horizon. The marginally outer trapped surfaces (MOTSs) that
foliate these tubes can have complicated geometries as well as non-spherical
topologies. In particular, toroidal MOTSs form inside both of the original
black holes during the early stages of a head-on merger that starts from
time-symmetric initial data [1]. We show that toroidal MOTSs also form in the
maximal analytic extension of the Schwarzschild spacetime as Kruskal time
advances from the $T=0$ moment of time symmetry. As for the merger simulations,
they cross the Einstein-Rosen bridge and are tightly sandwiched between the
apparent horizons in the two asymptotic regions at early times. This strongly
suggests that their formation is a consequence of the initial conditions rather
than merger physics. Finally, we consider MOTSs of spherical topology in the
Kruskal-Szekeres slicing and study their properties. All of these are contained
within the apparent horizon but some do not enclose the wormhole.
