His shield was made of an impenetrable material.
None. No material is indestructible.
Impenetrable- The fort's defenses were thought to be impenetrable.
The fortress walls were impenetrable, standing strong against any attempts of intrusion.
The man had impenetrable metal skin, incapable of being pierced.
Bwindi Impenetrable National Park was created in 1991.
Impenetrable is more of an Adjective, it's used to describe a trait, or as in Impenetrable, it's describing how something cannot be penetrated. Penetrate itself would be a verb.
impenetrable
The area of Bwindi Impenetrable National Park is 331 square kilometers.
The professor's heavy accent made the substance of his lecture nearly impenetrable.
Opaque.
The steel curtain