  It was recently pointed out that so-called "superhydrides", hydrogen-rich
materials that appear to become superconducting at high temperatures and
pressures, exhibit physical properties that are different from both
conventional and unconventional standard type I and type II superconductors
[1,2]. Here we consider magnetic field expulsion in the first material in this
class discovered in 2015, sulfur hydride [3]. A nuclear resonant scattering
experiment has been interpreted as demonstration that the Meissner effect takes
place in this material [4,5]. Here we point out that the observed effect, under
the assumption that the system is in thermodynamic equilibrium, implies a
Meissner pressure [6] in this material that is {\it much larger} than that of
standard superconductors. This suggests that hydride superconductors are
qualitatively different from the known standard superconductors {\it if} they
are superconductors.
