This note studies the geometric structure of monotone moment polytopes (the
duals of smooth Fano polytopes) using probes. The latter are line segments that
enter the polytope at an interior point of a facet and whose direction is
integrally transverse to this facet. A point inside the polytope is
displaceable by a probe if it lies less than half way along it. Using a
construction due to Fukaya-Oh-Ohta-Ono, we show that every rational polytope
has a central point that is not displaceable by probes. In the monotone (or
more generally, the reflexive) case, this central point is its unique interior
integral point. In the monotone case, every other point is displaceable by
probes if and only if the polytope satisfies the star Ewald condition. (This is
a strong version of the Ewald conjecture concerning the integral symmetric
points in the polytope.) Further, in dimensions up to and including three every
monotone polytope is star Ewald. These results are closely related to the
Fukaya-Oh-Ohta-Ono calculations of the Floer homology of the Lagrangian fibers
of a toric symplectic manifold, and have applications to questions introduced
by Entov-Polterovich about the displaceability of these fibers.