  A new kind of classically stable static solitons called metastable
quasi-topological defects (MQTD) and a systematic method to search for them is
presented, with examples from realistic particle physics models. They are
characterized by a topological winding number, which is not absolutely
conserved so that the MQTD may be converted to radiation by quantum mecanical
tunneling. The two-Higgs standard model (2HSM) supports the existence of
classically stable membranes for Higgs masses consistent with present day
phenomenology and with perturbative unitarity, as well as with loop corrected
MSSM. We also comment upon the possibility of metastable strings in the generic
2HSM.
