Remarks on decay of defects with internal degrees of freedom

We consider the decay of metastable walls and strings populated by additional degrees of freedom. The examples involve the decay of an axion wall in an external magnetic field, pionic walls, and metastable walls in dense QCD. It is shown that the induced fermions escape from the wall during the decay process, providing an example of the chiral magnetic effect. An absolute stabilization of metastable and unstable walls in a large magnetic field is found. A possible higher-dimensional generalization of the chiral magnetic effect is mentioned.